Decision Scripting - Excommunication

Hey fellow CK2 AGOT fans. Recently I've been working on an excommunication mod for a reformed R'hllor religion (via Tino's mod). The idea is that, as head of the religion, you would be able to excommunicate followers of the reformed R'hllor religion at will. To ensure the mechanic isn't abused the player will incur tyranny for unjust excommunications. This is my first mod but I have managed to create a working script by stitching together bits of code from other decisions and making a few tweaks. However, I've reached the limit of my scripting abilities and would appreciated some guidance implementing a few additional features.

• One of the potential ALLOW constraints is having the Azor Ahai bloodline. I've tried various iterations of 'is_bloodline_member_of = blood_of_azor_ahai' but the game isn't recognizing the constraint.
• Presumably an is_high_priority targeted decision shows up in game as a special character action? If so, it would be nice to have the high priority notification activate if you can justly excommunicate someone (when they have certain traits, etc.) but remain off if only tyrannical excommunications are possible.
  
• Excommunicating someone should allow for just title revocation (no vassal negative opinion). I've been experimenting with opinion modifiers and character flags but have had no luck in coding this successfully.
  

If anyone has suggestions for cool features and tips on how to code them I can give it a shot. I'd like to release the mod publicly once it's more polished. Any help is appreciated. Thanks.