You need a lawyer, if only to discuss this matter and understand all your rights and options as well as the process.
First, I assume that "Daddy" is your current husband. If you are not married, this will be very hard. Second, I assume that you have a child support order requiring the father to pay child support.
If those things are true, this is not that difficult, although it is tricky and must be handled well to avoid a problem. You would file for a step parent adoption and then ask the father to consent to the adoption, giving up his rights. The benefit to the father is that he gets to stop paying child support. Even if he has not been paying but you have an order, he owes everything that was ordered pretty much forever. Therefore, his resistance just encourages you to seek payment through contempt of court.
If you do not have a support order, then the response to his refusal is to let him know that you are going to immediately ask for support.
Finally, if you are not married to Daddy, then it would be very, very hard to get an order allowing Daddy to adopt.
By the way, while most lawyers require a retainer and provide "full representation" which means that they handle your matter for you and charge for everything, some attorneys sell "unbundled" or "limited" legal services where you pay for just what you need and can afford. For example, some attorneys will prepare letters for you to sign, or sell the paperwork for the court filings; then you can proceed on your own, but knowing that your paperwork is correct and having a road map as to how to proceed. Or who will attend a hearing for a flat fee even if they are not handling the whole case.
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