Revising a Lease Option Agreement

[Robert Burns]

I currently have a lease option agreement in place with the a FSBO seller and I typically assign these agreements for an option fee to tenant buyers who need time to obtain a mortgage to buy the property. However I am talking to a tenant buyer who wants to buy to home over the next 14 months by paying the owner approximately $10,000/month until the selling price is met. How do I modify my lease option agreement with the seller to enable me to assign it to this tenant buyer and still collect my assignment fee?