Petition to probate will

You are correct.  No one can give away something they do not have.  There is no reason for you to sign away your interest in the house.  If your sister wants to sell the house and you do not, your sister must first file a suit for partition.  You may want to buy her interest.  You may prefer to let her force a sale and take your share of the proceeds.

Please accept my condolences on the loss of your mother. You need to schedule a probate consultation with an experienced probate attorney in order to get advice on whether you should sign a given document- this forum is not intended for the provision of legal services in particular cases- it's for general information only. That said, there are a few issues in your post that i can address: 1. If your mother did not own an interest in a particular property at her death, then no, she can't give it to anyone under her Will. There may well be a fight about a provision in her Will that tries to give away property she does not. However, it is possible that she did own an interest even if her name isn't on a deed for the property- that depends on how the property came to be in the family. In many cases, people have inherited property interests without title paperwork ever being properly updated- in those cases, the property (often called heir property) is on record as held by its original owners but is actually owned by other people who received their interests through inhertiances. 2. In Georgia (I assume this is a Georgia estate, but if not this answer may not be correcte), a Petition to Probate Will does not give anything to anyone, and it should NOT contain any description of what the Will says. You should have gotten a copy of the Will with the Petition, so perhaps that's what you are referring to, but I can't tell from your post. If the Petition itself actually spells out what the Will is trying to do, someone didn't prepare the Petition correctly. 3. You aren't required to sign a Petition to Probate Will, if you don't think that the Will is valid and that it should be admitted to probate. But if you don't, then the person who put it together can file without your signature, and you will then need to be prepare to bring your challenge to the Will to the court quickly after that, or the Will will be admitted to probate without your consent. So, get a probate attorney with litigation experience to work with you if you believe that the Will is not valid and should not be admitted to probate.