I have skimmed most of the responses, but not all, so forgive me if there is any duplicate advice here.
I had a child almost four years ago, and did not marry my son’s father. I maintain a ‘close’ relationship with my son’s father - we speak on the phone almost daily, and my son talks to his dad, too. My situation has a unique challenge - my son’s father lives about six hours away so regular visitation is not possible. My family lives in the same area as my son’s father, and when I go to visit them (normally 1-2x a year), normally my son’s father (and my husband and I) and both our kids, all go out together for some activities - we have gone hiking in the park, to the mall, to Chuckee Cheese, to the movies, etc. Sometimes, my ex-boyfriend and I even go out alone (with my parents watching the kids) so we can discuss custody matters, or other arrangements.
How does my husband handle this? Like a man. He acknowledges that a relationship between my son’s father and I is in the best interest of our son/his step-son. I would not go so far as to say that he is "super friendly’ with my ex- and personally- I know he has a lot of raw feelings towards him - but he always acts cordially, and respects him. When my ex-boyfriend visits (and due to the distance, we always offer him a place to stay), my husband will engage him in talking, or various activities when he is able to.
I firmly believe that this course of action has helped things - and especially as our son gets older… I had a friend who had a daughter a long time before I had my son, and the split was terrible - it racked his daughter’s life and made everything more difficult… a parents job is to provide a secure foundation for childhood - the discordance of being “cold” and “detached” (or worse - arguing or openly negative!) can have serious consequences on a child… when dealing with a child it should NEVER be “US” vs “THEM” - a child should know only LOVE.
First, you need to acknowledge, as a third party to everything relating to your fiance’s daughter you do **not **have a say in what goes on regarding custody - your fiance needs to handle this. IF he does NOT handle this, then I would seriously think and pray about that.
As far as advice, your fiance needs to document everything. Document days that the mother didn’t drop the child off, when the mother changed arrangements, document, document, document. An informal agreement has NO legal standing for custody, and is non-enforceable.
First, is paternity established? Does your fiance’s name appear on his daughter’s birth certificate?
Second, what sort of custody rights is HE looking for? (I would not even get into grandparents rights at this time – that is their problem, not the OP or her fiance)
He has a couple options, depending on the state he lives in.
LEGAL CUSTODY - The right and obligation to make decisions about the child’s upbringing, for example: education, religion, and medical care. LEGAL custody can be SOLE (only one parent retains these rights) or JOINT (where both parents retain these rights)… Is he involved in the decision-making process?
PHYSICAL CUSTODY - who has the right to visit/live with the child. This one varies a lot by state, but again, it can either be SOLE (ONLY one parent- usually not applicable unless one parent is deemed unfit), JOINT (50/50 living situation), or PRIMARY with visitation - this is the one that sounds most like fiance’s situation currently. It is important to make sure that VISITATION is outlined in the legal agreement in order for it to be enforceable.
For example, with my son, I have shared legal custody and sole physical custody with visitation at my discretion.
In most states, paternity, custody, and child support are three separate issues and can be handled together, but they do not have to be. For example, we have legally established both paternity and custody, but we have not established child support through the courts. My son’s father pays through voluntary support.
I recommend that you do not have any contact with the mother of your fiance’s child, except through your fiance. No letters should be sent to her.
Personally, you want to make sure you stand back and let the main players figure this stuff out - otherwise, yes, it will get ugly. It’s not your business. As far as the grandparents go, again, that is something that your fiance will have to work out WITH HIS PARENTS after he moves out. Right now, since he is living with his parents, there’s really nothing to be done. I would tread very softly here, and be kind, because for as long as this little girl has been in their lives, his parents have been giving her a place to stay so he can spend time with his daughter - I would definitely consider that. My parents, on the other hand, gave me no such reprieve.
I would be interested to know your fiance’s thoughts. Good luck.