Talk:Halloween Princess/@comment-30582955-20171110001104/@comment-4817837-20171110115811

The game automatically locks all 5-star CEs as soon as you get them so you don't burn them by accident. Keep one of the CEs locked and unlock the other four copies you want to feed into that one by holding down on each CE and tapping on the padlock icon to unlock it.

After you unlock them, you should be able to select them for feeding purposes.

Also, the game doesn't let you feed CEs that are currently in any of your Party setups or your Support list, so make sure to take them out of there as well if that's the case.