AJ McLean is fully supportive of his daughter’s wish to change her name. The Backstreet Boys singer’s nine-year-old daughter recently changed her name from Ava to Elliott, and he insisted that he and his wife Rochelle are behind her no matter what. AJ told PEOPLE: “When my daughter asked to change her name to Elliott, initially, I didn’t know if it was a transgender thing, which it is not, but it is a personal choice. And it is her body, it’s her name, it’s her everything. And she’s still Ava. She’ll always be Ava to me. “But at the same time, whatever reasoning it is, that’s hers, and I’m goi…