If they pledge and donate a portion of that 50% back to A, A steps into the shoes of that basis, but is responsible for a portion of the gift tax that B's heirs face from the donation.

Mine was more in the form of a one sided gift.  

Make it a welcome package or "Thank you for being a long time tenant" gift.

I think someone in my oversized family may know the owners but I have not spot checked :) End goal is to gift the project to mommy to host her family functions :)Guidance on this deal is appreciated!

He loves to do it when he is here etc....We do really like dealing with our tenants.... we screen really hard for good ones that bring *us* gifts at the holidays because we take good care of them.

And the financial gift was selective. 

He will gift me the $35k difference, which I will use as equity for a downpayment.I'm confused about using the equity he gifts us as a downpayment to purchase this home.

So, next Christmas, my suggestion would be, to go to Amazon and buy up as many "chicken Little" books as they have, and gift them to all the people that told you about this "bubble",...and told you to wait to invest until,...until,...I'm still not clear as to when they think their sky would stop falling.

It's disrespectful to throw away such a nice gift from your guests/tenants. 

Depending on the title maybe your uncle can take gain under his tax free section 121 and then gift your mom half.