@shrimpusa
You're probably right about there being multiple ways to skin this cat; that's usually true with Excel.
To help sort out which of those multiple ways might make more sense than the others, it would be useful to learn a bit more about the context here, the scope of such things as:
- roughly how many students are involved in being scheduled regardless of time
- the number of students who have special schedule limits or prohibitions (the group you're asking about)
- the volatility of the two populations (how frequently do people get added to or subtracted from the lists)
- is it only lunch and recess times or are there other "special slots" applicable to some and not others
- are there some who can ONLY do lunch or recess (or some other idiosyncratic requirement)
- anything else you can think of that would help understand the bigger picture
