Can I take over my sister inlaw payment to acquire her rental?

[Nilo Ignacio]

My Sister inlaw has a house here in San Antonio Texas.  She lives in Hawaii and she wants to get rid of her rental property because she no longer wants to be a landlord.  I am a self employed and I would have a higher interest rate if I try to buy it out right..  

I want to pay her cash for her equity and take over the house. She has a long time tenant and would like to keep the tenant in there.

What would I need to do? 

Can I be added to the deed?

im not sure if the house is assumable. probably not..