GMB951: I haven't used a 536 or a 996 but....I had a BC346XT for a number of years and in the custom search you could choose a Control Channel Only option where if it hit a control channel it would start tracking the audio of that system, changing freqs as needed etc. is that what you are talking about?
if it is....then i think you may be outta luck. I have a BCD436HP and have yet managed to find a way to do the same thing. as a matter of fact last night i hit an unfamiliar digital freq in a custom search, no audio, and kept toggling between LNK and DAT, no NAC shown. to check on what it was using the 436, i had to create a new system and a new site, then after making sure the ID search function was enabled, on that new system, and it was in an active Faves group, i THEN went to the analyze function, chose System Status AND then finally was able to see what i had. that is the simplest way i have found so far, which defeats the whole purpose of using the function you describe with the 996, if i have interpreted your question correctly that is.
it is possible i have missed something on the 436 and/or that the 536 can do what you want it to, but as a user of two similar scanners, i don't think it can be done, at least in the way you would like.