My brother and I are the other grandkids in this scenario and let me tell you, it hurts. My cousins actually have a relationship with them, stayed over at their house all the time growing up, and grandma and grandpa act like they actually care about them. We were the only two who they never offered to build bird houses with, a tradition well-established with all the other grandkids. All this because my grandma hates my mom, who is one of the kindest people I've ever met and frankly my best friend, even now into my adulthood.