Ariel Winter -- Back In Court Fighting Mom -- Now Dad's On My Side, Too

"Modern Family" star Ariel Winter now says her father is taking HER side -- opposing her mother, Chrystal Workman, in the battle over Ariel.

Ariel says in court docs -- obtained by TMZ -- daddy Glenn is happy that her big sis Shanelle is Ariel's guardian. Up to this point Glenn sided with his estranged wife.

Ariel doesn't say why her dad has flip-flopped, but it's interesting ... he's not asking to become the responsible parent. He's happy that Shanelle has assumed that role.

There was a hearing today ... nothing set in stone, but the judge said when everyone goes to court to fight it out over who gets custody of Ariel ... his inclination is that Ariel should NOT be forced to testify, because she's a 15-year-old girl and forcing her on the stand could be psychologically detrimental.