On my scanner, I have my counties trunked system in a couple of ways.
1. Trunked, ID SEARCH, all garbage groups locked out and talkgroups 1,2,3,4 saved.
that way if things get busy, I can change from ID SEARCH to ID SCAN so it will only scan the Sheriff's four dispatch groups.
2. Trunked with nothing locked out, to hear everybody
3. Trunked frequencies put in manually, and set to conventional in case of system failure. (fail soft)
4. The input frequencies and conventional, to only hear them if they are within a mile or so. It will hear everybody.
and the 1,2,3,4 thing is the sheriff's dispatch numbers. someone must have OCD.
so you could do the same with your trunked system, I just don't know which one.
ID search means the radio searches for any talkgroup, so the ID SCAN means you can only scan the talkgroups you saved into it.