Affidavits of heirships

[Bil Casimir]

I have a house under contract. The home heirs went to the daughter and son. Title company says her sister is next to kin and her sister kids have to be notified and appear at the closing? The sister died 30 years ago, and we only have the siblings names not addresses. The person who has the house has a will that was never probated. Not sure how to handle this.

This was the actual Title Company response: 

You can do 2 things either.

1. Have 2 affidavits of heirships one for Ollie & Essie . Keep in mind that we will have to list all of the Heirs and since you have not spoken with neither of them? They all have to be here at closing.

2. You will have to go to court and have the original will probated.

Any suggestions? The case is located in Houston, Tx