Wirelessly posted (BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
My condolences on your grandmother's illness.
Was each family member's ticket booked as a roundtrip award, or as two one-way awards? My understanding is that once the first flight on an award issued with BA miles is flown, no changes are permitted to the remaining segments, even for a fee. Whether BA will make an exception upon proof of your grandmother's illness, I do not know.