Guardianship Question

I know I need actual legal advice but I’m just curious if anyone knows - my husband and I are estranged from my in-laws due to various reasons. I had the most random thought today and so I am wondering, if something were to happen to both my husband and I could his family contest who we name as guardian for our children? I don’t think that they would because they have had zero interest in our boy up to this point but I feel like they might do something out of spite to make my family miserable. Are there ways to safeguard against this?