Not necessarily. On our first family cruise, my sister was silver because she had cruised
DCL before. Only she was given a lanyard at check-in. (And we were staying Concierge because for some reason that's what my dad booked.) So I would not count on them being given lanyards and count it as a bonus if they are.
The real question that - at least to me - was not clear in the OP's post is if the 2 daughters are in a separate cabin than her. If they are in a separate cabin, then she should call and make sure that her Castaway number is applied to her cabin correctly. If they are in the same cabin as her, it's a moot point because as has been said, everyone in the cabin shares the highest status.