I would just caution about putting up to much Due Diligence money up front.. and be realistic about your financial capacity.

If it is a Join Ventur, that would be different than them supplying funds in a lending capacity expecting a return. 

Since my parents still have capacity for more conventional loans we are exploring that avenue where they acquire via conventional financing and I exchange with the proceeds in to a couple SFH with the cash.  

If you suspect funny business:Do you have any relationship to this tenant other than in a professional capacity?

If so have you worked in an assistant manager, store manager, or district manager capacity?

You have to first evaluate the condition and capacity of the existing building and then determine the density of a ground up.

This gives her legal capacity to sell. 

That's what we should all be preparing for to whatever capacity we're able.

That can only be answered once we know the extent of the work needed to get the property earning at full capacity.

If your big system has enough capacity, and you're going with option #3 - I'd just put dampers in for balancing issues.Baseboard heat would only make sense as a cheaper alternative to a new unit for your 'other unit' ie: you block your duct-work to one unit, then use baseboard heat in the other, presuming your electrical is separately metered.