Instrument change at the same point as key change - how to remove unwanted key signature?

Suppose I have a player holding clarinets in Bb and A.

The music for the Bb Cl is in F (concert), and when player switches to the A Cl, the key changes to D (concert).

The score, in concert pitch and galley view, looks like the first attachment.

In the part, I get a pointless key signature change to 4 flats when Dorico generates the “To Cl in A” message, as in the second attachment. Is there any way to get rid of it?

This has been discussed here
and here
and it looks that this is not yet implemented.

I thought I remembered some discussion on this, but for whatever reason I didn’t find those threads.

To be honest I also remembered those discussions, but they’re difficult to find because the search tool filters out “key” and “change”. I ended up searching for them in Google.

A possible solution that comes to my mind is to create a blank custom key signature, which would be an equivalent to an atonal time signature, in which the naturals are blank symbols. This might work, albeit I haven’t tried it and can bring up some spacing issues that need adjustments.