Joan and Bernard Carl are being sued for nonpayment by the celebrity wedding planner who designed their older daughter’s wedding. (Carl family photo)

Washington A-listers Joan and Bernard Carl wanted a beautiful wedding for their oldest child. And for the most part, they got it.

The lavish June 2015 celebration for 250 guests in the garden of their Southampton, N.Y., estate was gorgeous. The bride wore Oscar de la Renta. There were 3,500 white roses individually studded into the lawn, a five-course dinner beneath massive chandeliers of greenery and a seven-tier wedding cake.

The mother of the bride commissioned monogrammed napkins for each place setting and a custom fabric for the tables and the flower girl’s dress. There was a beachfront rehearsal dinner. The reception included a specialty cocktail served in an ostrich eggshell; the after-parties offered a Calvados and cigar bar, plus hot chocolate and brownie stations.

A week later, the couple exchanged vows in a small candlelight ceremony in the 16th-century chapel at the family chateau in the Loire Valley, followed by hot-air ballooning the next morning. Both ceremonies were featured in Brides magazine last year with the headline: “This Couple’s Multi-Day Wedding in the Hamptons and in France Will Blow You Away.”

But behind the scenes, there was drama. So much drama that the wedding nearly got called off.

Planning a wedding can make anyone crazy. Adults go their entire lives not caring about table linens, and suddenly they’re fighting about whether napkins should be white or ecru. Costs spiral out of control because you simply must have that food truck for midnight doughnuts. But when a wedding budget tops seven figures, expectations and emotions can run exceptionally high.

So maybe it’s not surprising that a legal battle is brewing between Los Angeles-based celebrity event planner Mindy Weiss and the Carls. Weiss, who designed the Southampton ceremony — which the Carls acknowledge cost upward of a million dollars — is suing the couple for more than $340,000 in unpaid fees and expenses, plus $1.4 million in damages. The Carls claim that Weiss went on an unauthorized spending spree on their dime and is holding the bridal video hostage unless they pay her inflated bill.

“I think there are people who prey on people’s love for their children, they prey on their vanity, they try to take advantage of it,” says Bernard Carl. “I think that’s a really sordid part of life that, if you have the good fortune of having some affluence, you have to live with. But it doesn’t make it pleasant.”

Weiss did not return calls seeking comment. But in the lawsuit filed last month in U.S. District Court for the Eastern District of New York, she contends that she worked “feverishly” to plan the wedding and covered more than $267,000 in expenses out of her own pocket — with the Carls’ permission, via what she calls a “Vendor Advance Contract.”

The Carls contend that Weiss was hired to consult and recommend other vendors but was never authorized to enter into contracts on their behalf. Yet they say she did just that, hiring favored L.A. friends at outrageous prices instead of New York-based companies as they requested.

In retrospect, it was probably a bad fit from the start. Weiss, “Party Planner to the Stars,” is best known for extravagant, over-the-top weddings for celebrity clients such as Sofia Vergara, Ellen DeGeneres, Gwen Stefani, the Kardashians and ABC’s “The Bachelor.” The Carls, who have homes in Kalorama, the Hamptons, London and France, move in elite social circles but keep a relatively low profile. They are horrified that the private family celebration and subsequent lawsuit, first reported in London’s Daily Mail, have become tabloid fodder.

“It is clear to me that we didn’t do our homework on Mindy, that her very Hollywood aesthetic was just a really poor match with our objectives and image for this event,” says Carl during an interview in the library of his Kalorama home. “And we didn’t sense that early enough. That was our mistake.”

The Carls — he’s an investor and lawyer and co-owns D. Porthault, the French luxury linens company, with his wife — hired Weiss in May 2014 to plan the wedding of their older daughter, Alex. They had interviewed a number of elite planners and sought advice from their longtime friend and florist, Jeff Leatham, who says he suggested Weiss “without hesitation. She’s one of the best in the industry.” After she interviewed with the bride-to-be, the Carls tapped her and paid half of her $50,000 consulting fee.

Initially, everyone was excited — it was, after all, the first wedding of the Carls’ three children. The couple say they told Weiss they were willing to spend up to a million dollars but didn’t want a “glitzy” event. They say they asked repeatedly for a detailed proposal, but Weiss kept putting them off. They became concerned but stayed quiet because they didn’t want to upset the bride-to-be.

That proved to be a huge miscalculation — by the spring of 2015, the relationship between Weiss and the Carls had devolved into finger-pointing, angry emails and demands for money.

Things came to a head when, after nearly 10 months of planning and just six weeks before the wedding, Weiss finally provided a budget that came in at $3 million. The father of the bride was stunned and refused to pay some charges that he considered to be wildly inflated.

In the lawsuit, Weiss contends that the Carls “expressed an interest in an extravagant affair, never mentioning the word ‘budget.’ ” That assertion is “absolutely, unequivocally, totally untrue,” says Carl. (The event ended up costing more than a million, although he would not disclose the final tally.)

“In mid-May, this wedding was very close to being almost canceled,” Carl says. “At one point, I told Joan I was prepared to write a very big check to the kids as a wedding present, cancel the wedding and sue Mindy. I was done. I was really done.”

Event planner Mindy Weiss is known for designing extravagant, over-the-top weddings for celebrity clients such as Sofia Vergara, Ellen DeGeneres and others. (Tiffany Rose/Getty Images for Wedding Paper Divas)

Days before the wedding, Leatham attempted to intercede and got into a testy email exchange with an angry Carl, who wrote that he is the “hound from hell” to anyone who causes pain to his family or attempts to take advantage of them. (The two men made up; Leatham says he was paid “every cent I was due” for his floral designs at both ceremonies.)

An executive with another high-end event company, who is not part of the lawsuit and spoke on the condition of anonymity because he knows Weiss and Leatham, said that the mistake was not nailing down a dollar figure for the affair far in advance. “We get a number from the client, and we design a wedding to that budget,” he says. And his business never pays vendors with company funds: “If the client doesn’t cut the check, they don’t get the wedding.”

The expenses Weiss says she paid for upfront include more than $45,000 for her staff to work the wedding, $48,000 in travel expenses, $38,000 for lighting, $10,000 for the videographer, and more. All those little wedding favors add up, too: $4,300 for totes, $5,000 for T-shirts, $1,000 for hangover Tylenol pouches.

The Carls paid for the caterer, the florist, the photographer, the band and other services directly. Aside from what he considers excessive charges, Bernard says he also has a lot of issues with the service Weiss provided. The caterer and the band weren’t given a schedule for the reception. Heel protectors (which keep stilettos from sinking into the grass) didn’t work. The hired dressers had no clue how to bustle a wedding gown. The brownie station was poorly lit and sparsely attended. The bride and groom’s dogs, which were in the wedding procession, were left out of the wedding photos. Weiss didn’t have a Plan B for rain, which started to fall just before the ceremony.

He also says that Weiss promised that the wedding was her only event that June, a claim he says her own social media account disproves. Instead of a customized event, they got Weiss’s go-to Hollywood excess. He’s willing to pay about $100,000 of the “legitimate expenses” in the outstanding balance — once Weiss releases his daughter’s wedding video.

Weiss’s lawyer, Menachem Bensinger, did not provide a copy of the “Vendor Advance Contract” and confirmed that it was not included in the exhibits given to the court, adding that some contracts are oral or “implied.” He did not respond to questions about other details, including the alleged hostage wedding video.

Hindsight is always 20/20. The Carls admit that they never would have allowed a business deal to continue for months with the same misgivings. But it was their first wedding, and emotions got the better of them.

What should have happened, according to industry experts, is that the Carls should have fired Weiss as soon it was clear that they were a bad fit — or Weiss should have quit.

Alas, no one pulled that trigger because no one wanted to upset the bride. And now: a messy and public lawsuit.

“Everyone had Alex’s best interests in mind,” says Leatham. “It hurts my heart that this is happening.”