I spend 9 months making a needle turned Hawaiian quilt for my step son and his lovely bride. After the wedding, I took this bride to a day spa. We saw them on a regular basis. Nothing was ever mentioned. If figured in this case "if you can't say something nice don't say anything at all". (Everyone else that saw it was more than impressed.)
In your case, however, I would guess that since the family was in such an upheaval for a while, they all think they thanked you, but don't realize that they didn't.