Should we decipher that as the homeowner making a sales agreement to Party 1, who in turn assigned the sales agreement to Party 2, who in turn entered into a "lease to own" contract with you? If so, I hope that you had a lawyer review all of the contracts involved and ensure that you will be able to enforce your contract at the end of the two years if one of the other people involved decides that it is not enforceable.
If you are in a "lease to own" contract exclusively with Party 2, the only person who owes you any duty is Party 2.
In terms of "invalidating" your contract with Party 2, if you have decided not to purchase the property as agreed then the usual consequence of walking away from "lease to own" is that all of your payments are treated as rent. If you have a two year lease term and break the lease early, you may be liable to your landlord for lost rent as your landlord tries to find a replacement tenant. Beyond that, you will need to have your actual, written "lease to own" contract reviewed by a lawyer to determine how its terms affect your rights and remedies.

