Qadha Salaah

Qadha namaaz

Q: If anyone starts to offer 5 times namaz at any time of his life, so is it mandatory for him to offer all the due salats (Qaza-e-umri) first, which he has not been prayed since he was 12 years old?

Non-heir discharging the fidya for the missed Salaahs of the deceased

Q: Previously I asked about a man who passed away but for the majority of his life did not pray Salaah. As per your previous reply, fidya can be given on behalf of the deceased: What do the Ulama state about a person who is not an heir but is related to the deceased, can they give the fidya on his behalf? Furthermore, how does one calculate the fidya per Salaah?