First I'm sorry your aunt is so poorly. As others have mentioned, I think that BA would likely waive the change fee upon the death of a close family member (even though technically, I'm not sure if an aunt would qualify, I suspect a supervisor will agree to that). However, they almost certainly would not create award space if there is none, even less so in CW or F. As others have mentioned, if you wish to travel on an award ticket, I would make a booking in WT or WT+ (if that's what available) on a date you feel may be a likely travel date and if you need to change because of a funeral give them a ring to ask if the fee might be waived.