As far as I konow you would have to go landside when going from T1 to T2 and take a bus or tram over and add 2x security checks to your travels. I would strongly advise to stay airside in T1 for the layover of your parents. And I'm quite sure they wouldn't even let you into T2 airside without a bording pass for T2.

If they really want to leave T1 and walk a bit I would suggest walking into the squaire center (Long distance train station) where there are some restaurants like a inhouse bavarian beer garden. Or go to one of the lobbies of the Sheraton and Hilton Hotels, relaxed places to stay for 2 hours with a coffee or tea or a snack.