OK, first of all, I have a couple of questions for you to think over and REALLY think over before you read anymore of my post. I am in NO way trying to be mean or harsh, but am thinking about the child, and you need to be in a place where you are being totally honest with yourself FIRST before you can truly think about her needs before your and her biological father's feelings first..........
Number 1- Why is it important to you (or your fiance) what she refers to him as? Am I correct to assume that when she is with him, she simply calls him "Dad"? (not "step- Dad") I assume that the term step - Dad is just her way of differentiating between the 2 Dads when she is talking to others, whether it be you, her Mom, or someone else, correct?
Number 2- Why does your fiance only have 1 day per week visits with his child? Has he ever expressed any interest to the child's mother in having more or longer visitations? Possibly a few overnights or school vacations to be included in his visitations?
Number 3- why does the child have the mother's last name and not his? Was this a choice, because he was not determined to be the father at the time of birth, or at the mother's insistence?
Number 4- since he is paying child support, is he paying through a court order, or does he pay on his own, through an agreement between him and the child's Mother.
Ok, now that I have my questions out of the way, I will tell you why I have asked them.
First of all, as far as saying that your fiance is her "step- Dad", and the other father figure in her life is her actual "Dad" is fairly common in these types of situations. It is not unusual for a child to consider the man they live with and who takes on the role as "Dad" 24 hours a day 7 days a week their "real" Dad. Real and biological mean 2 different things to a child that age. Her step father is very "real" to her in every aspect of the word. He is there for her, all the time, no matter what. She can rely on him, (hopefully), no matter what is going on, at any time any day. He is also the "Dad" with whom she shares her siblings. In her mind they are her "real" siblings. She doesn't understand that they have different fathers at this point. (she could, but it doesn't sound as though anyone has filled her in up until now) Now, all of this being said does not in any way diminish your fiance's role in her life. He is very important and plays a huge role for her! She needs him as well! Obviously, she knows that he loves her and that she can count on him as well, and feels fairly comfortable with you both, or she wouldn't have been speaking to either of you about the different "titles" that she has for you.
If your fiance has not already requested more and longer visitation with his child, I would suggest that he do so immediatly. He needs to have as much time with his child as possible to have a strong bond with her, and also so that she knows without a doubt that she is loved and wanted by him as well as her "other" Mom and Dad. Even if he is not able to get all of the time that he has requested, just knowing that he WANTS her to spend more time with him will go a long way in the future with his child.
If the child has her last name for any reason other than it was what HE wanted for her, and unless he is comfortable with her keeping it at this point, I would strongly consider having her do some sort of name change as well. Even if she doesn't change her last name at this point, (which could be confusing to a 7 yr old), you could request that she have his added to part of her middle name or be hyphenated in her name just so it's there. After all, she is a girl, and let's face it, MOST girls DO change their names when they get married. (NO IDEA what is up with the step Dad taking the Mother's last name there. Do you have any idea why that happened?) Also, if for some reason he was not determined to be the father at the time of birth and that's why he was not on the birth cert, PLEASE tell me he did do a paternity test , just to protect him. Not that it would really matter at this point if he is already a Dad to this child and in his heart he loves her and she is his daughter, but for legal reasons, he needs the proof. Trust me, he doesn't want THAT one thrown at him later if he tries for more visitation and can't get it because they tell him he really isn't Daddy. UGH!
OK, last I asked about the child support. If he is paying through a court order, then why wasn't there some type of visitation put into place at the same time the support order was done. I know they are sererate issues, but the judge can usually do both to keep you from having to go back another day. If it's because the Mom was being "reasonable" at the time and was agreeable , but now is not, it will look good for him that she is much less now. (especially if he has been paying regardless of how often he has been able to see his child) One thing to remember, child support and visitation do not determine each other. It works BOTH ways. The court will not keep a Dad from his child for failure to pay support, and will not allow more visits because they pay more. Child support is to help financially support your child. Visitation is to help emotionally support your child and bond with your child. Both are neccesary for the child to thrive and do well in the world.
This child is VERY lucky to have 2 Dads who love her so much, and soon to be 2 Moms as well! The title is not so important as the time spent, and the quality of that time. Please don't get too caught up in the little details of it all. Remember that she is only 7, and her definitions are going to be far different than an adults, and really the most important thing is to make sure that she is safe, happy, and healthy. Once you know your real reasons for why this even is eating at you and bothering you so much, then you can decide for yourself if it is really worth getting into a discussion with the Mother about it all. I think it comes down to hurt feelings, and more of a Dad wanting the step Dad not to be taking his place. However, nobody can ever truly take his place if he stays in his child's life and doesn't allow it. It is really up to him. I wish you the best!