Okay kiddo, let me explain this to you in a way that makes sense. So, sometimes people can have step-grandparents or adopted grandparents, but this is a little different.
So, imagine your mommy had a baby and that baby was you. Then, your daddy remarried and your step-grandma had a baby who was your half-sibling.
Now, when you grew up, you fell in love and got married to someone who also had a child from a previous relationship. So, that child became your stepchild.
Now here's where it gets a little tricky. Your stepchild's biological parent, let's call them Fred, is also your mommy's half-sibling. So, that makes Fred your half-nephew.
Now, Fred grows up and has a baby of his own. That baby is your step-grandchild because you married their grandparent. But since Fred is your half-nephew, that baby is also your half-great-nephew or half-great-grandchild.
And so, through this complicated family tree, you can be both a grandparent and a great-grandparent to the same child because of the different relationships in your family.
In short, it's like a puzzle where you have to connect different pieces of your family tree to figure out all the relationships, and sometimes it can get a little confusing, but it's still all about love and family!