Novel research: Aunt getting custody of kids

Hello everyone. I am writing a novel and was hoping there might be someone here who would be interested in sharing experiences of gaining custody of relatives? The situation in the book is that the husband and wife both pass away and the children are placed with the wife's sister. If you have gone through something like this, or know someone who has, I would be very interested in asking you some questions. Thank you so, so much. Also, if you know of books/movies that would also be very helpful.