Family Law Questions? Ask a Family Lawyer Online.
Abandonment occurs when a parent or guardian either desserts a child without regard for the child's health or safety or fails to provide necessary care for a child living with them. The child's mother has not abandoned the child under Either part of that definition. However that doesn't mean you still can't seek guardianship over your grand daughter – it just means you wouldn't necessarily receive guardianship under that particular element
You can argue constructive abandonment because the mother has effectively abandoned the child by choosing not to care for her. However she hasn't left her without regard for the childcare. She knows the child is safe in your care. It is somewhat of a technicality… But the constructive abandonment argument is nonetheless valid and beneficial to you
You can argue that it is in the best interest of the child to be in your care, that you are the only parents she has known and that you provide her with the physical contact and emotional support that she needs and her mother is essentially just a visitor in her life. There are never numerous courts that would allow you to argue child abandonment in addition to constructive child abandonment. I would assert boats under the category of abandonment.
Your best bet however is to attempt to get mom to agree to transfer custody until such time as she is able to care for her child, if that is something you are amenable to doing. Please let me know if you have additional questions or you need me to clarify anything.
* apologies for the typo. The word boat should have been BOTH.