That is very noble of you. I think every state and situation is different. It is definitely not an easy task though. You'd need true evidence that they were incompetent parents. Not just kind of poor parents but they have to be pretty bad to remove custody and guardianship of the kids. Are they abusive? Neglectful? You'll need documentation and evidence. And then you'll need the same kind of documentation and evidence that you would be a fit parent yourself. Your work history and income, living situation, family that currently lives with you, your background will be looked at, etc. Can you afford an attorney to help you?