Switching resorts in a package??

[Blessedx3]

Hi we are in the midst of planning a very spur of the moment trip. We are booked at 2 different resorts the BC and CR right now and would really rather be at one, because we have little ones. If in the next few weeks something opens up at either so we could stay the whole week can we change without paying a fee/penalty??? I am sure this has been answered before but the searchisn't working for me. We will be traveling 2/6-2/10. TIA!!