You will need to work out a mutually-agreeable solution. 

I have a dilemma on which direction to begin first.

I use Rentec Direct and I can just archive an application.

Offer to buy them a few indoor portable heaters until you find a solution. 

We would like to have more individuals that we deal with directly. 

Please direct Mr.

@Helena Goyvaerts send me a Direct Message and I will be able to help and point you in the right direction.Thank you

If I understand correctly; the seller would receive 80% ($40,000) directly from the mortgagee at closing and would enter into a personal agreement with me for the 20% down payment ($10,000) in which he would be reimbursed separately from my mortgage payments at a separately agreed upon rate and term?

Your instinct to speak directly to the PM and not through your realtor is spot on.

Once verifying see if you can talk to the buyer directly & explain the 90-day flip rule and see if the buyer is willing to wait 2 weeks before submitting his offer.