I am married and have a 2 yr old son. I have a 24 yr old daughter from a previous marriage. If something were to happen to my wife and I, who would have the main legal right to him? His 24 yr old sister? Either of his grandmothers? My mother in law currently lives with us to help us out with him, does that factor in? I'd like my daughter to have him. I have not had a chance to update my will but was curious who would have rights to him. Thank you

No one has a "legal" right. What you need to do is to prepare appropriate documents that will lay out what you want to happen. Durable Power of Attorney and a will update(codecil) is where you would start. Otherwise, the state will determine what happens.

You and your wife should speak to the person you want, and put it in writing.

If not, those who want custody, would have to approach the court and the court would decide