Jennifer Aniston and fiancé Justin Theroux have already reportedly disagreed about exactly what kind of wedding they want, and now reports say the couple had a small argument about who would be allowed at the ceremony.

Theroux allegedly upset Aniston when he asked if his ex-girlfriend Heidi Bivens could attend the couple's upcoming nuptials, the United Kingdom's Now Magazine reported.

"[Justin] must have had a 'brain fade' moment. Jennifer hit the roof when she saw that he'd put Heidi on the guest list," a source told the magazine.

Theroux reportedly supported his decision by explaining to Aniston that Bivens had been a part of his family for a long time and had connections to his relatives, but Aniston put her foot down and refused to allow it.

"Jen snapped back, saying she was going to invite her exes John Mayer, Brad Pitt and Vince Vaughn," the source said. "That seemed to help resolve things because now they've agreed no exes are to be invited."

Ex partners of the couple aren't the only ones banned from the wedding ceremony. Aniston has also reportedly barred her mother, 76-year-old Nancy Dow, from attending her daughter's big day.

The actress and her mom have had a tense relationship since Dow gave a revealing interview about her daughter and wrote a tell-all memoir. Dow was banned from Aniston's wedding to Pitt in 2000.

Aniston originally agreed to allow her mother to attend the wedding to Theroux, but she changed her mind after she felt Dow was gossiping about the wedding too much.

"After her star-studded $1 million wedding to Brad, Jen now wants a much less formal and less publi­cized ceremony," a source said. "And she believes Nancy's loose lips are a threat to her privacy."

But it's possible the rumors about Theroux and Anison bickering over Theroux's ex are just that - rumors.

Erroneous reports about the couple have sprouted frequently, including a claim that Aniston demanded Theroux get a nose job before the ceremony, which a friend of the actress said was false and "laughable."