Subject to-Can Seller buy another property?

[Matthew Yrungaray]

Can a seller that agrees with me to sell "subject to" get a new mortgage right away to buy a new house. If I provide a letter stating that I was covering the mortgage, would the seller be able to turn around and buy another home?

My seller has 2 condos. One is under water and the other is above water. The 2 condos in combination have positive equity before selling costs. He is very motivated to get rid of those and buy a bigger home for his family. I was considering offering a "subject to" deal for both and then turning around and selling them via lease option. My biggest question is, Can the seller buy a new home with the sub-2 in place?

Thanks all