Basic Idea: Room of Requirements.
Hold Umbridge by luring her in to hold her and only her
Objections:
1)Room reconfiguration
A:The Ravenclaw Diadem was not accessed until someone needed that room again.
2)Anytime someone else accessed her room, they'd let her out.
A)Use a password-locked holding cell. This way, even if they do get into the Room, they'd still need to get past the cell door.
Hold Umbridge by luring her in to hold her and only her
Objections:
1)Room reconfiguration
A:The Ravenclaw Diadem was not accessed until someone needed that room again.
2)Anytime someone else accessed her room, they'd let her out.
A)Use a password-locked holding cell. This way, even if they do get into the Room, they'd still need to get past the cell door.