Hello. I'll be happy to assist you.
There are two things you can do, although neither is a guarantee to work. First, you can file a motion to strike the agreed order you signed. You would do so on the grounds that you were deceived when you signed it. Thee the judge would look at the circumstances, what representations were made at the time you signed it and how that differed from what was originally proposed. The difficulty there is that parties are presumed to have read and understood a document before they signed it. Again, it all comes down to the circumstances.
Second, you can file a motion to modify the child custody
order as it stands. Once an order is put into place, it is not necessarily permanent. As circumstances change, sometimes the custody order needs to be changed, too. There are a couple of issues here, too. First off, your custody order may specify a time period you must wait before filing some motion to modify. If it doesn't, you at least don't have that to deal with. Secondly, you need to show that the circumstances have changed so significantly since you signed the order that it is in the best interest of the child
to now modify them. Depending on the age of the child (the older the better), that reason could be that the child wishes to live with the other parent, school issues, extended family
contact, etc. You are obviously in a better position to know what those circumstances are than I am, but that's an option, as well.
I hope that answers you question. If not, feel free to ask follow up questions. If so, please remember to "Rate" my answer before you go. Good luck.