Release of Claim to Exemption for Child of Never Married Parents Who Do Not Live Together

TurboTax explains the use of Form 8332 to allocate the exemption for child of divorced or separated parents.  But what, if any, form should be used for the case of the child of parents who are not married and don't live together and have not created any kind of formalized custody agreement? This particular situation exists for my unmarried daughter who gave birth in 2023 and with whom the infant has been living full time.  What is the significance of answering "No, I don't have a custody agreement"?  Should my daughter ask her daughter's father for a custody agreement?