ITR Return Revise 2 yr old

Hello Everyone,

My dad was given a gallantry award posthumously , we have been getting family pension ever since. I  recently received a letter from my father’s department , regarding the award that he received, has been made at par with other awards such pvc ppm, and the family pension we receive will be exempted under 10(18). The letter mentions the notification dated 30 aug 2017. So, my query is , can I revise the return of previous two years, i.e. ay18-19 and ay19-20, given the fact I received the information late , which is not my fault.But Both the return have already been processed.

Thanks