I did not understand your first paragraph reference to first engage vs any subsequent engage. Is there a behavior difference between the intial vs subsequent press of the disconnect?
My experience is that if Sync Buttons are set to Sync, the AP disconnect will sync hdg / alt irrespective of CWS config for Hold current Heading or Last Heading. Is this the correct behavior?
As for the background on my second suggestion, given the behaviors noted above, lets say an IFR departure is being performed, CWS should be configed prior to departure to Last Heading and Sync Buttons off, heading / alt bugs set to desired and disconnect pushed at the appropriate time in the departure to capture desired preset hdg/alt. This config scenario works fine.
Moving forward to the next flight, that configured behavior may not be desired - assume a VFR departure and at some point, an urgent need to just hold hdg / alt - if pressing the disconnect at this point (and I have done it - forgetting what I had configured) you get whatever the bugs are set to and the mad scramble starts to set bugs (and recover from what george was set to do).
Of course, prior to pressing that disconect, you could go into the AP menu for Hdg and Alt and set sync then press the disconnect - its a couple of buttons to click and the head is down for all that while flying.
I suggest that a straight and level button would be helpful. Similar idea to the 180 button.
To directly answer your question, I have what I need for today closely enough. Just making wishes.
Thanks