Subject says it already.
Instead of adding every user individually to my buddy list,
I would like to allow only a certrain membergroup to send me PM.
Is that feasible somehow?
no
The closest you can get is that membergroups can manage who is able to send PM's in general (ie, to anybody) but it can't restrict sending to a specific individual.
Are you willing to manually input code into your forum's files? If so, it's a 10 minute job.
Why not (unless there's a mod-solution).
there is no mod for this. Don't think it's ever even been requested before.
Can we move this to the MOD-request-section then pls?
Done.