If you were adopted into a family who also had biological children, did you feel treated differently as an adult family member?

My husband was adopted but his parents had 4 biological children. My MIL and FIL were great, but now that they're gone, the siblings completely ignore us, specifically our children. A prominent cousin seems to go out of her way to ignore us. When a daughter of my FIL from an affair surfaced years ago, the family latched onto her with more veracity than my husband, and accepted her easily, which is great for her. But me and my kids are not in the loop. They talk to their brother (my husband).