Need Help IMMEDIATELY need to know how to structure new contract

[Joseph Riv]

Okay so I have a one page purchase agreement on a house under contract. I have a buyer that wants to buy the home , and my seller wants this mans trailer home included as part of the sale(sort of as an exchange) How would I add that to the new contract they would in turn be signing. I have my assignment contract all dolled up and signed as well as my discharge agreement. 

Last questions typically how much is closing on a home or how can I find this out since nobody is open on the weekend.