Ariel Winter -- Back with Her Other 'Family'

While her mother and her sister battle it out for custody, 14-year-old Ariel Winter returned to the place where she's needed the most ... the "Modern Family" set.

Winter was spotted in L.A. a few days ago, taping a scene with castmate Sofia Vergara.

During the shoot, Winter was carrying a mystery cooler, Vergara was carrying an iPhone and the gay uncles probably were out doing something stereotypically flamboyant.

As we previously reported, Sofia ... just like Ariel's older sister Shanelle ... has posed for a few racy photos in her career, like the one below (taken last week).