one waiting-room message for personal and another for scheduled

[22nd]

We have a need to switch from using personal meeting rooms to using scheduled meeting rooms.
The issue is that the custom personal meeting room links are already on invites that have gone out to people. 

We want to set a "this meeting has not yet started" message that directs people to where the new meeting room is but does not show up for the people in the waiting-room if they are in the correct meeting.

Is there a way to do this?