When to finalize a seller leaseback agreement

[Richard Cazier]

I'm selling my home with a closing date one month prior to moving out, where I will negotiate a 30-day seller leaseback with the buyer. The buyer's agent wants us to sign the home sales contract first, and then work out the details of the leaseback agreement later as an addendum. In my mind, the details of the leaseback ($ amount, etc.) should be negotiated before signing the sales contract, otherwise I am signing a contract with closing date and no guaranteed leaseback. How hard should I push to have the leaseback agreement in the sales contract? I am selling in Texas.