what I would do is....
1 assess what it is they want changed, is it important ?
2 assess the impact $ wise, and then do same as 1
3 inform the other side, they they are now delaying settlement where you acted in good faith to resolve the matter on terms both sides agreed too
4 tell them you will seek to have the signed agreement shown to the court as you will seek costs if forced to go to trial
I am not a lawyer, but if I was in your shoes, and let us say both lawyers thought a 50/50 arrangement was just, you all made effort to get agreement and sign it, and other side now wants another 10 or 20% for example - just because, or, so they can drag it out for whatever reason, and if the advice you get is that the request is not fair or just in an experienced lawyers eyes, then ask if you should just request a trial date, assuming you are far enough along, and let other side know this is not a game, let them know you will seek costs. Submit the agreement and finish, or they are choosing to litigate.
So you just need to really weigh it up, if other side is asking for small adjustments, or something not of large $ value, then you have to be careful that it is not you continuing to litigate over something the court will see as insignificant.
I would also ask that if you were agreeing to some new terms, that the other side now make allowance for costs to change things and re sign etc again, if you agree to the changes.
At the end of the day, you really have to decide what you can live with. And if the court is likely to think what you would like is reasonable and just. The courts want both sides to sort things.