Written contracts cannot be verbally changed. A contract can be enforced if only one person signs it, particularly against the ones that signed it.
A contract must have a promise or obligation from one party in exchange for a promise or obligation from another party. There is no requirements that contracts be signed, witnessed, or even written to be enforceable. Oral contracts as well as contracts written on napkins in bars have been enforced by courts. A contract only requires that both parties are doing something in exchange for whatever the other party is doing.
Only the person who signed is a party to the contract. The tenant who didn't sign is not bound by the lease.
You pay only what you agree to pay in the contract. If the mediation fee was not addressed in the contract, each party will pay their own mediation fees, as agreed to by the mediator and the party prior to the mediation.
Only if the contract allows for it.
You can only back out of a signed contract, if the contract states there is a backout clause. If there is no clause stating you may back out of the deal within 24 hour, you are liable for the contract signed.
Only if both parties agree to dissolve the contract or the contract was an illegal contract or it was signed under duress.
A leasing contract would typically be signed when and only when the occupants of the home and the leaser both agree to the terms in the contract set up.
READ the contract you signed. Most possibilities are covered in the contract. the only way I know of to "cancel" a contract is if it was started at you home(usually door to door sales) or default by one party and usually involves legal action.
Not necessarily. The party that did sign it can be held to the contract, but only if the other party is relying on that and performed their part of the agreement. And depending upon the course of dealing and what has occurred between the two parties, there may be other reasons to hold that the contract is valid, even if neither of the parties signed it.
It is not necessary to have both signatures. It certainly helps if there is a legal issue. If the other party signed it, you will likely be able to hold them to it. Oral contracts can be valid as well. The difference would be dealing with real property (land).
If your question is "can the contract be null and void" if signed only by the primary buyer and not by the co-signer? Depends. If the contract is in both names-yes. If the contract is typed up "only" in the buyer name-no. If the loan is conditioned to both signing, yes.