If the heirs are aware that their deceased parent is liable for many Qadha Salaat and Fasts, is it obligatory for them to pay fidyah or kaffaarah?

Answer

If the mayyit (deceased) had made a wasiyyat (bequest/directive) that fidyah, kaffaarah, etc. should be paid on his behalf, then it is compulsory to fulfil the wasiyyat and pay the fidyah, kaffaarah, etc. from one third of his/ her assets.

If a wasiyyat was not made, then it is not incumbent on the heirs to pay fidyah, kaffaarah, etc. for the deceased. However, if they wish to do so, then each one should give from his/her share and it may not be imposed on any heir. Furthermore, nothing may be taken from the shares of minors.