Bob-  Thanks for your reply.  The reason for the concern over the reverse mortgage interest is that she inherited a substantial sum of money in 2022 and about 100K of it is taxable.  So, I'm looking to offset her tax liability with allowable deductions.  Since I know her original purchase price, the percentage of land to improvement of the rental property, the precise date it was first rented and the last day it was rented, with no other improvements during that period, I can figure out pretty closely what the prior depreciation must have been.  Certainly I feel comfortable that it's a reasonable number and fair to the gov't and to the client.  

During the time it was a rental, there was a CPA handling her returns.  He is no longer in business.  No forwarding address or number.   Thanks, again...