We know of a single mother in a similar situation (although in our case, the father is now deceased) – and to ensure that her child would be cared for by her choice of parents (me & my husband) she gave us Legal Guardianship papers to sign shortly after the child’s birth.
She had a friend who was a lawyer who was willing to help her prepare the paperwork and her will free of cost – and we just went to our local bank where there was a notary to observe our signatures. The entire thing cost no one anything but their time – and we set it up shortly after her son was born.
The purpose was this – she didn’t want the father involved (and he wasn’t) with her son and she also didn’t want her son raised by her parents if something happened to her. Because we’re already raising her daughter, she wanted her son (our daughter’s half-brother) to be raised by us if something happened to her.
In our case it’s kind of a moot point now – because the father died a few years ago…but in the event that something happened to the mother, her will and the legal guardianship papers are clear in their intent that we should raise her son.. not her parents, not her sister or brother’s family.
As @gailcalled points out – a will is not an ironclad reason for a child to not be given to his biological relations..but it sure makes clear what the parent’s wishes were for their child.
Legal Guardianship papers cinch that up even tighter – and allow us to act immediately (we can take him for medical care, pick him up from school, etc.) and legally should the mother be incapacitated.
This is just my humble opinion..but part of being a responsible parent involves these sorts of matters. Communicate your wishes to your family (or dearest friends, if you’re estranged from your family), prepare a will, get life insurance and make sure your children are listed as beneficiaries for your policies.
We’ve even gone so far as to create a printed document stored with all our financial paper work with a list of points of contacts and policy numbers—and we showed our closest kin where to find this info in our house in the event something happens to us.
My in-laws, parents and siblings know who we’ve chosen to care for our kids if something happens to us.
I think it’s doubly important to do this sort of thing if you’re a single parent..because it’s simple math, right? One less person around to sort things out if something bad happens.