From what i understand the daughter was always the cash cow for the family or mother.Happens in many parts of thailand the daughter has to provide for them.Now she is dead the mother is getting the last of the possible money if allowed to take off the suspects.This is thailand and if another parent or mother loses a child the same will happen.
Happened to a friend and thai wife,man drunk wrong way up the road hit the car dead.Took many family members to harrass them,but not they fault.But in the end the thai wife said just pay them the money so they leave us alone.It cost them a 1,000 pound 60k in baht and was not harrassed again.This is thailand and a not very nice part of culture