Subject To... Can I write off the Mortgage Interest?

[Stephen Rockwell]

I have an accountant that recommended that I have the sellers sign an addendum that says they "are not claiming the mortgage interest, they no longer have an equitable interest in the property and they are transferring the right for me to claim the mortgage interest as I am the one paying the mortgage even though they are on the deed of trust." I felt that I was missing something here as I haven't came across this topic in the forums before.

QUESTION: 

When buying "subject to" for a long term rental is there a boilerplate document to use for claiming the mortgage interest? A standard type document that investors use in this scenario? 

Is there some simple verbiage I can include in the Purchase Contract? (If anyone can share an example of the verbiage that would be great!)

Also I heard there are some new tax things President Trump is passing regarding claiming mortgage interest and will this apply to business holding a rental such as my subject to properties? Anyone know or have a reliable source to learn about the new tax plans?

I would like to hear any advice or tips as to what other investors are doing with their "subject to" rentals regarding claiming mortgage interest.

Thanks guys!