Legal Heir Certificate Issue

I have received two properties in a single plot from my mother (A) and her sister (B) through a settlement deed in 2019. They received the property through a partition deed in 2008 after the death of their sister (C) in 2006. C was divorced in 2000 and had no kids. Their parents had too passed away in 2002 and 2007 which made A & B the only legal heirs to C and thus the property owned by C was transferred to A & B in 2008. Since my prior deed was done 12 years back, no one remembers whether the legal heir certificate was obtained during that time or not. Now when I am trying to apply for a home loan, the bank is insisting on getting a legal heir certificate which I believe will take a lot of time. I would like to know whether there is any workaround for this problem. We do not have the divorce documents at our procession which were received 20 years back. So I believe applying for a legal heir certificate might not be possible.