The custody battle between Arizona (Jessica Capshaw) and Callie (Sara Ramirez) is still unfinished in the next episode of "Grey's Anatomy" season 12.

The former couple started to be at odds with each other when Callie decided that she will take their daughter Sophie with her and her new girlfriend Penny (Samantha Sloyan) to New York. This did not sit well with Arizona, since she will not allow her ex-wife to bring their daughter all the way to the East Coast.

In the previous episode, Callie enthusiastically revealed her plans to Arizona over breakfast. She told her that she and Penny already found a two-bedroom apartment near several schools which Sophie could go to. Arizona stopped her, saying, "I need to take a big step backwards. Somewhere, sometime, you heard me say yes to this. You heard me say, 'Yes, please, Callie, take my daughter across the country' but I never said that."

Their argument went out of hand. It even prompted Arizona to get a lawyer so she could file for full custody of their child. Callie got furious with Arizona's move, making matters worse.

In the trailer for the upcoming episode, titled "You're Gonna Need Someone on Your Side," the former couple will put their friends in a very compromising position by asking them to pick a side between them.

Meanwhile, Meredith (Ellen Pompeo) will urge Amelia (Caterina Scorsone) to give her relationship with Owen (Kevin McKidd) a chance so they can officially become a real couple.

The synopsis for the upcoming episode reads:

"Stephanie's relationship to Kyle becomes complicated. Meanwhile, Meredith encourages Amelia and Owen to take a chance and choose to be a real couple. Arizona and Callie are at odds and put their friends in the middle of an uncomfortable situation."

"Grey's Anatomy" season 12 episode 21 airs on Thursday, April 28, on ABC.