We are brand new to real estate investing and are not sure how to go about this deal.

The buyer(s) might offer $515k with a 3% seller concession towards buyer(s) closings costs. 

If each building belonged to a different owner, the only thing that they would have to collaborate on is, obviously, the courtyard (gardening, each side has it's own sprinkler system) , the intercom (about $120/month for the phone line), and the parking area (needs resurfacing).  

It's so much more than the deals we close. 

It's just that in this market deals are few and far between and I don't know when or even if I could find another deal soon.

How did you find this deal and how did you negotiate it?

I am looking for a template that will calculate the a maximum  cost to purchase a fix and flip , with a variety of financial options and then a template to manage all project costs.

I honestly don’t want to deal with her ever again.  

I've been looking at opportunities from investment firms like Open Door Capital, et al, and I would like to know if anybody has a recommendation for a spreadsheet or tool for analyzing these deals?

Also, we just landed another deal so that gives me an excuse to stay focus on stabilizing this asset in the next few months.