PSTN forwarding (Microsoft Calling plan)

We are using Microsoft Calling Plan and have assigned 10-digit numbers to staff.

One admin assistant is handling incoming (external) calls for their supervisor who does not want the PSTN calls ringing him directly in Teams.  But with forwarding on, we're noticing ALL calls - including web and video, and including internal calls - are being forwarded.  While this is useful for some scenarios, traditional delegation would call for distinguishing incoming external PSTN calls.

What "clean" options do we have to forward the external PSTN calls to the assistant?  I feel like this should already be an explicit setting in the Teams Call settings... 

Ideally the supervisor would retain the line for outbound and dial by name.  I'm guessing I could create (yet another) call queue and assign both people, then opt out the supervisor (who does not want the incoming PSTN calls ringing him directly in Teams).  But that means we lose outbound calls unless I assign a separate line to the supervisor and turn on an outbound caller ID policy that maps to the (now shared) line.

Thanks!