software to track a promissory note and existing mortgage with a subject to purchase

[Erik Bringleson]

Hi,

I recently purchased a single-family home using subject to financing. I took over the existing mortgage and am paying the seller monthly for their equity. I know I could throw together a google spreadsheet to track payments and equity remaining balance, but wanted to see if there is any low cost or free software to better track and report this promissory note?

I am pro member so i have access to rentredi, but i dont see a way to track this. Any help is appreciated.

Erik