Usergroup Permission

I have two roles on the "councillor" and "secretary" website and forum. The task is to implement the possibility of private messages in such a way that users with the "council member" role cannot initiate chats and cannot write to each other, but at the same time they can see private messages from users with the "secretary" role and respond to them. Removing the checkbox from the "Can write PM" setting for users with the "council member" role leads to the fact that "council members" cannot really exchange messages among themselves, but they do not see private messages if they were written by a user with the "secretary" role. Is it somehow possible to configure? Thank you!