At the point no16 in that answer, you have told that a person on the death bed should make a will to pay the fidiyaa for his/her qadaa salats. My question is that if this will is not made by some-one due to unawareness of this fact, then can his/her children still pay fidiyaa with the intention of the fidiyaa for the missing salaat of their deceased relative? Or can his/her children pray some qadaa fard salaat on behalf of deceased relative? Or both methods are correct.?
If a person did not make Wasiyyah (bequest) to pay Fidyah (compensation) for
unfulfilled Salaats, then any person, for example, child, may give the
Fidyah on behalf of the deceased.
It is hoped that Allah will accept the Fidyah. It is not permissible to
perform Qadhaa Salaat on behalf of another person.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai