California: Do My Adopted Boys Have Rights To Their Biological Mother's Estate After Her Death?

Location: California

I need some advice from anyone familiar with California wrongful-death or probate law.

My two boys were born to my sister-in-law, who struggled with drug addiction.

I first took custody of my oldest nephew when he was only 6 months old. I fell in love with him and raised him. When his mom got sober, I supported their reunification, even though giving him back was heartbreaking.

Unfortunately, she relapsed, and I eventually took him back in—along with his baby brother, who was only 9 months old.

At around 5 years old, my oldest told me something I'll never forget. He said he loved staying with me because I had a bed, a bathtub, and a toilet.

That sentence broke my heart.

I eventually adopted both boys. I became their dad.

I always hoped their biological mother would get sober again and that, someday, they could have a relationship with her.

Then in 2024, she was struck and killed by a patrol vehicle.

That was it. The possibility of her getting better and reconnecting with her boys was gone forever.

I filed a wrongful-death claim because I wanted to protect whatever rights or benefits might belong to my boys. But I was told that my two adopted boys have no rights to their biological mother's estate/claim.

What makes this even harder is that they have an older biological brother who is still a minor, and I'm told his attorney chose not to include my boys in the claim.

I'm raising these two boys as a single father. My youngest is autistic. I'm not trying to take anything away from their brother, and I'm not looking for a handout.

I'm trying to understand whether my boys actually have legal rights that may have been overlooked.

California attorneys, probate attorneys, or anyone who has dealt with adoption + wrongful death + a biological parent's estate: is there any possibility my boys could still have a claim or inheritance rights?

I know Reddit isn't a substitute for an attorney. I'm just running out of places to turn, and I don't want to find out years from now that there was something I could have done for them but didn't.