Bought my girlfriends niece and fiancé airfare to come from Denver to visit gf for Christmas... she loves her dearly and misses her.. bought about a week ago...flight is nov 29

Bad thing is, is that they are now moving back here before Christmas.. I'm not sure if they know when yet, but I didn't get insurance or anything... I should have but didn't... it's 99$ a ticket to cancel/rebook for another time... which is about half of what I paid for the tickets.

Do I still let them come back or do I rebook for myself at the another time? (I'd still be out 200$)