Give the possibility to exclude a list of pages from the list of locations where a content template is available

For example:

• page A is in the list of available locations for the template T
• page A has 2 children : B and C
• by default, T is available on B and C as well

I would like to be able to exclude B from the list of available locations. This way, T would be available from A and C, but not from B.