2 Family NYC Purchase

[Twinkdogs]

I am currently 25 and I own a Coop in Yonkers NY. I purchased it 4 years ago for $90k and it is worth a little of $160 today. The reason I am writing today is I am seeking advice on purchasing a 2 family property (3 beds over 3bath) from my grandmother. She has been there for over 50 years and the house if fully paid off. I will essentially be getting the house for a price of 80% of the market value perhaps even less. This is because she is not dealing w/ a broker and also b/c I am her grandson. I will be purchasing this jointly with my girlfriend I was hoping to get advice from someone as to the tax treatment or how I should handle this transaction. I pre-qualified for a loan regardless of how we handle this transaction. Please let me know if you have any questions or need any more information. I thank you all in advance for your help.

Thanks,
Steve