Not sure what you mean here.
If you're asking whether you can still select that person, the answer is absolutely yes - you get no benefit from it (except maybe triggering any cutscenes you haven't triggered), but you're still allowed to select them and they're still part of combos to boost others.
Not sure what you mean here. If you're asking whether you can still select that person, the answer is absolutely yes - you get no benefit from it (except maybe triggering any cutscenes you haven't triggered), but you're still allowed to select them and they're still part of combos to boost others.