Notifying Grandparents

I am in the process of adopting my 2 step daughters and we have everything done and a court date set but my husband was told we have to write a letter to their grandparents (their biological mom's parents) notifying them of the petition for adoption since the mom is no longer living. Any examples or suggestions for this letter on what to say?

I have never done this so I can't give you an exact layout, but I think it would be important to include in the letter that by adopting your step kids, you are not trying to replace their daughter and that you will always honor her memory. That you love the children and want to give them another mom.