Is it a valid contract?

My dad left a property (without a written will).

The heirs are us ( the children) and my mother.

My mother entered into a contract with a thrid party to lease the property left by my dad.

We (the children) have not even seen/signed the contract.

He have not yet partitioned the estate. The property is still under my parents name because we dont have money to pay Estate tax.

my question is, is this a valid contract signed ONLY by my mom? Can her signature in the contract represent us?

should we (the children) be a signatory as well since we co-own the property with our mom?

Lastly, my mother did not apply for a business permit for the lease.

NOTE: I have no intention to put my mom in a bad legal position BUT we feel the contract signed by her only favors the tenant. I am finding a way if we can redo the contract that is beneficial to both the tenant and my mom.

Thanks in advance

technically, the lease is valid for the portion your mother owns, and that will be definitely more than 50% of the property because she owned half by her own right plus her share of the inheritance.

you can try to nego for the share of the children, but if the tenant refuses, you will have to file a case in court to change or cancel the contract.

can a contract of lease be amend? How?
1. lessee signed the contract - oct 2010
2. lessee want the start date be move at Jan 2011.

once a contract is perfected, it can only be amended with the consent of the parties.