After you enter the 1099-Q, the interview will give you a screen titled "Student". On the list on that page, select "A beneficiary that's not a dependent on this return". You will then be given a screen to enter the expenses directly.
You have to coordinate with the other parent. Even though the expenses may have been totally paid by the 529 plan, she is allowed to claim the tuition credit. You must reduce the amount of qualifying expenses you use for the 529 plan earnings exclusion by the amount she uses (usually $4000) to claim the credit.
