Purchased a building via hard money lender, when note came due we had a friend purchase the building for us. They hold the mortgage but we make the payment and have an office in the building (its considered residential). We can't get a warranty deed because that would (could) cause the mortgage company to eslcalate the note. Need something that would prohibit them from selling it from under us if this ever go sour. HELP??

If I follow you, your friend took out a mortgage in their name on the property. So they own the property and the lender has a lien against it.

What you need is a contract for sale. That states that you will pay the mortgage and when the mortgage is paid, they deed the property to you. Also that you will have the right of first refusal if they want to sell.