HAVANA » The business ideas have ranged from a bikini franchise to a peanut farm, restaurants, and design firms for software and home interiors. But even more novel than the pitches — in a country where entrepreneurship used to be illegal — is the financial muscle behind them: Cuban-Americans whose last business ventures were seized by Cuba’s Communist government.

"It’s all about people not losing hope and seeing that starting a business is a way to improve their lives," said Eduardo Mestre, 65, a Wall Street banker who returned to Cuba last year for the first time since 1960 to see the startup training he helps finance. "Emotionally, it’s very hard not to connect with people who have all this ambition in a place where maintaining hope is very hard to do."

Many of the first Cubans to leave after Fidel Castro took over are beginning to come back, reuniting with the island they left in bitterness, overcoming decades of heated opposition to its leaders and partnering with Cubans in direct new ways.

Some are educating a new crop of Cuban entrepreneurs to take advantage of the recent limited openings for private enterprise in Cuba. Conservative Republican exiles in Miami have also helped finance the renovation of Cuba’s most revered Roman Catholic shrine. Even young heirs to the Bacardi family, which fled Cuba after the revolution, leaving behind luxurious homes and a rum business that employed 6,000 people, are sending disaster relief and supporting artists while Alfonso Fanjul, the Florida sugar baron, recently acknowledged that he had gone back to Cuba twice, meeting with Cuban officials and later declaring that he would consider investing under the "right circumstances."

It has been a shocking reversal for a community of exiles that has long represented an immovable pillar of support for the U.S. embargo against Cuba, and some Cuban-American lawmakers have responded with outrage. Rep. Mario Diaz-Balart, R-Fla., called Fanjul’s trips a "betrayal."

"The question is, How can we better help the Cuban people free themselves from this regime that has been there for over half a century?" he said in an interview. "And the best way to do that is to deny funds to the regime in any way we can."

But what has emerged in Miami, New York and elsewhere over the past two years, as President Razl Castro has opened the economy, just a crack, is an alternative approach that emphasizes grass-roots engagement, often through churches, as a tool for giving Cubans skills and independence from the state. Among many Cuban-Americans who now describe themselves as a part of a diaspora, rather than exiles, a new sense of responsibility — to Cubans on the island, not to the property they lost or to fighting the Castros — has gathered strength.

"We think engagement, dialogue and interaction — lowering the barriers — is the best way to develop civil society, but also some of us who feel some respect for the 11?million people stuck there, we just really feel that’s the right thing to do," Mestre said. He added that he had sought a new relationship with Cuba, despite the loss of his family’s homes and businesses, including what was once Cuba’s largest television and radio network, because "the loss of our property and wealth is kind of secondary to the feeling about what happened to the country and its people."

The expanding exchange of people, ideas and money is the direct result of policy changes over the past few years in Washington and Havana that have opened up travel and giving for Cubans and Cuban-Americans. After decades of being cut off by politics and geography, the airport here is always crammed with Cuban-Americans coming to see family and lug in gifts, just as it is now more common to see Cuban artists, academics, and dissidents in Florida or New York, where they often mingle with the established Cuban-American elite.

"The broad trend is Cubans, regardless of their politics or ideology, coming here to visit, live and work, and go back and forth," said Julia Sweig, director of Latin American Studies for the Council on Foreign Relations. "It’s an organic dynamic in which the elite are participating."

For many families, the transition from keeping Cuba at a distance to pulling it close has taken time, and multigenerational discussion. Older and younger members of the Bacardi clan began returning to Santiago de Cuba, the birthplace of their family’s spirits business, in the 1990s, despite the company’s bitter dispute with the Cuban government over Havana Club rum.

"It accelerated my interest in not losing touch with the culture," said Kevin O’Brien, 45, president of the Bacardi Family Foundation, describing trips with his mother. "And seeing what could be done to improve the lives of the people there without all the jumping around and saber rattling."

When he and some of his cousins decided a few years ago to take charge of the family’s long-dormant foundation, they agreed to focus much of their support on Cuba, returning to a version of an old family custom: relatives pool money together and distribute it to a chosen cause or person.

Not everyone gives; there are about 500 Bacardis now, and as with most Cuban families, O’Brien said, disagreements over the homeland are common. But since reactivating the foundation in 2012, the Bacardis have raised $28,000 for water filters after Hurricane Sandy and financed efforts to encourage creative expression, with art, photography and music.

Cuban officials seem tolerant, up to a point. Eager to grow their weak economy, they welcome the money but fear its power, said one of the artists supported by the Bacardi Family Foundation who insisted that his name be kept secret to avoid trouble with the authorities. He added that while Cuba’s leaders had become more welcoming — no longer calling exiles "gusanos," or worms — they were still distrustful, determined to keep Cuban-American influence from becoming an immediate challenge to the state.

For now, experts say that seems unlikely. The organized money going to Cuba, beyond an estimated $2.6?billion in family remittances, mostly from the United States, remains relatively small. A lot of it is still funneled into the Catholic Church, one of the few institutions allowed to play a role in civil society. The Order of Malta provided 800,000 meals for the elderly in Cuba last year with around $250,000 in donations, mostly from Cuban-Americans in Miami.

The Cuban police have nonetheless interrogated some of the old women being fed.

Cuba Emprende, the nonprofit organization where Mestre is on the board, has also struggled to reassure Cuban officials that its founders — a bipartisan mix of exiles long dedicated to engagement and others who only recently embraced the idea — are interested only in acting as an incubator for small businesses, in line with the government’s stated economic policy. The organization’s official tax forms filed recently with the IRS show that the firm has dispersed about $225,000 so far, and that none of it came from the U.S. government.

But board members say that Cuban officials continue to suggest that Cuba Emprende must be part of a covert Washington plot. A Cuban instructor in Havana, who asked for anonymity to protect the program, said the pressure had been increasing as Cuba Emprende had grown; as of mid-March, 731 graduates will have completed the 80-hour course, which is run through the church in an old seminary here and at a rectory in Camaguey.

Cuban-American lawmakers who continue to support the U.S. embargo also seem displeased with the increased engagement, even though Cuba Emprende and other groups active in Cuba stress that their work does not violate the embargo, falling under humanitarian or other exceptions.

Sen. Robert Menendez of New Jersey, the Cuban-American Democrat often described by Obama administration officials as Washington’s main impediment to broader changes in Cuba policy, said it was simply ineffective.

"I’m not seeing this engagement produce the results they say it would," he said, adding that "the regime hasn’t become more open" even as Europeans travel and invest in Cuba, unfettered.

But Mestre contends that Menendez and the other embargo supporters in Congress are being counterproductive. "With that attitude," he said, "you’re just hurting the people you’re trying to help."

And increasingly, many Cubans and Cuban-Americans are using the limited policy openings to build their own relationships, reveling in the surprise of a rediscovered connection.

"Cubans are Cubans," said Niuris Higueras Martinez, 39, one of Cuban Emprende’s first graduates in 2012. "We find ways to work together."

That bond is now evolving alongside, or within, Castro’s limited opening to market ideas. Higueras, a whirlwind of a woman who had always dreamed of opening a restaurant, now owns Atelier, one of Havana’s most popular eateries. Cuba Emprende played a major role in making it happen.

"Everything in that course was important," she said. In addition to the basic knowledge on how to calculate her books or change her menu for slow season, she said she benefited from the sense of a shared mission with her classmates and the accountants and other professionals Cuba Emprende relies on for help in Cuba. "There was just such chemistry," she said.

Now, in her business and others, there is a demand for more opportunity, more possibility — and the usual barriers. Cuban law and the U.S. embargo prohibit Cuba Emprende from bankrolling its students’ ideas as it would like to. Without enough capital for more ambitious ventures, including Higueras’ dream of opening a cooking school, some ambitions are just visions.

During the nightly dinner rush at Atelier, however, with foreigners and Cubans enjoying food and service that had disappeared from Havana for decades, Higueras seemed more interested in focusing on how far she had come. She said she took comfort in knowing that her restaurant made her customers happy, and her workers dignified.

"If you have 15 employees, you have at least 10 families whose troubles are suddenly resolved," she said, wiping a few drops of chocolate from the corner of a plate on its way out of the kitchen. "If you open a little, you get a lot."