Are My Aunt & Uncle Keeping My Mom's Share Of The Sale Of My Grandparents' Home?

Some important information:

Location: Texas

My grandmother passed away when I was a little girl.

Then my mother passed away.

Shortly after my mom passed away, my grandfather passed away.

Then a few years ago, my uncle passed away.

I'm not sure if my grandparents left a will.

Okay, so...

Last night I was on the phone with my dad, and he told me that one of my aunts and one of my uncles, who supposedly "own" my grandparents house, want me and my siblings to sign on behalf of my deceased mother so that they can put my grandparents' house up for sale.

He also told me that my aunt and uncle are worried about the child support that my deceased uncle never paid. They think the state of Texas will take that unpaid child support from the sale of my grandparents' house.

So, I told my dad... If they need us to sign on behalf of my deceased mom and they are worried about my deceased uncle's unpaid child support...does that mean that EVERYONE should get a portion of the sale?

Are they trying to keep all of the money?

Why else do they need us to sign on behalf of my mom in order to sell? Why else are they so worried about my uncle's unpaid child support?

What can I do in order to get the truth? I don't care about the money. I care more about them getting away with this...

I just hate that people get away with stuff like this... especially when it's done by your own family members. And the disrespect to their deceased sister and brother, and their children...

I'd appreciate any advice. Thank you all!