If he died after pesach, is in coma or ran away you dont have any problem as has been explained to Joseph year after year in the “buying chometz back” thread.
If he dies during pesach that might be a problem, though again not an insurmountable one. T is likely comparable to Joseph’s subscribe and save which is a beferish din as to what to do. Though I’m not sure about the land sold to the guy which contains hefker chometz