Thanks everyone! Cleared up my confusion.
My original booking is a suite with 3 people (dad, mom, child), $250 deposit pp. Will it work if I just cancel my newly created booking since there is no cancellation fee and with refundable deposit, then I can change the original suite booking into the one I want, exactly like "the cancelled newly created booking"?
What happens if my change will result in only mom and dad in the new booking? Child will have a new booking with someone else not in the original booking. Can I keep my child deposit after the change?
Anyone have experience about this?