Ashlee Simpson’s divorcing parents both attended the birthday party of her son.
The singer’s mother Tina and father Joe recently ended their marriage amid claims the dad is gay.
However they both went to support Ashlee’s son with ex-husband Pete Wentz, Bronx Mowgli, at his birthday celebrations.
A source told Usmagazine.com: "Joe arrived first and made sure to leave before Tina got there. It was very clear they didn't want to be there at the same time and are not on good terms.”
Apparently Joe mainly kept to himself at the party, and reportedly hugged both Ashlee and Bronx.
Ashlee and her sister Jessica are said to have taken opposing sides in the split. The witness continued: "[He] was hiding as he walked down the street with a hooded sweatshirt on. He looked like he didn't want to be seen."
Meanwhile 28-year-old Ashlee played nice with her 33-year-old former love and his current girlfriend, 24-year-old model Meagan Camper.
Speaking about the fourth birthday at the Coop, a play space for kids in Studio City, California, the source said: "The party was great - super fun."
While Nicole Richie was there, sister Jessica and her fiance Eric Johnson plus daughter Maxwell Drew, were not.
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