While your situation may (or may not) be the more likely outcome, realize that only the elite member themselves is "supposed" to get the elite benefits, not everyone else. Almost everytime I have traveled with others and booked more than one room, everyone in both rooms has been able to get CL access, breakfast benefits, or even room upgrades, but again, the program rules don't require that. So I when I do book multiple rooms, I come in not expecting the benefits to be applied to all rooms, but am definitely happy when they are.

So as I stated earlier, don't plan on your parents getting the room upgrades and other elite benefits and then get angry/disappointed if they don't get them. If it is important enough that they get an upgrade room, then book the upgraded room. No disappointments then.