What grounds can my ex use to appeal our agreement?

I am not able to comment on the terms of the agreement, because I do not know what those terms are and doing so would be outside the scope of this blog. Also, I am not aware of what statutes, ie, Divorce Act, Family Law Act, Children's Law Reform Act, etc., are applicable and therefore whether there are any additional restrictions on any potential appeals. For example, Section 21 of the Divorce Act sets out provisions relating to appeals. In addition to any of those issues, you would also need to determine what court to appeal to and what type of order was made either the Divisional Court or the Court of Appeal, assuming that the original court is the Superior Court of Justice - regular or family branch. There are differences between final orders and interim orders. In some cases the party wishing to appeal needs "leave to appeal". This means a motion to the court seeking permission and explaining why the court should hear the appeal. There are certain requirements in relation to seeking leave. To start an appeal some information, such as, transcripts, will need to be obtained. Finally, there is an appeal based on fresh evidence and certain requirements concerning a motion pertaining to circumstances in which new evidence that did not exist at the time of trial may come to light. Unfortunately, it is simply not possible to provide a direct outline of the issues in these particular circumstances.