This is making me think Chrollo is going to find Camilla. That said, even if he does steal her ability he won't have it for long given her temperament.
Random thought, more than one of the princes are Beyond's child. Considering how long he's been preparing, it seems likely that he wouldn't take a gamble on how long before his father dies and having a prince (his child) be young enough to be easily controlled.
The most likely ones I think are...