Waterpark Day Switching Resorts

[T- I Double G errrrr]

We now have part of our group arriving a day before the rest and were initially planning to do the Waterpark that day. Howeverince one will be arriving early they will miss the free ticket on arrival day. If they book at a different Disney hotel the day prior and then move to the same hotel under a new reservation the next day will that count as a new check in day? What if they do a separate reservation at the same hotel and just switch rooms/reservations?