I suppose it comes down to your ex's reasons for wanting to have the child benefit.
... if it's from a sense of equality - that the CB should be split between the two of you because you have a shared care arrangement in place and splitting the CB would reflect the equality of roles that both mother and father have in the children's lives then I would think that would be a good thing.
... of course, if his reasons are from an element of control then that would be a negative thing and I would question whether his motives are child-centric i.e. we share the care so we should be able to share the benefits and entitlements that CB extends.
You may find out that CB cannot be split. This is down to the rather out-dated system HMRC runs, basically the IT infrastructure cannot cope with a splitting of CB, this is a bit of an anachronism in this day and age when a large proportion of parents separation whether married or not. It's an either or with CB - you either are eligible or not. 99% of CB is in the mothers name as the CB application forms are usually in with the Bounty packs and HMRC routinely assume that the mother will be the prime carer, despite the changes in parenting patterns in this day and age.
for example, I have a shared residence order for my daughter - which the court has legally stated that both me and my ex-wife are equal parents in the eyes of the law, medical authorities, education authorities etc. I feel this is very important for my daughter as my ex can't control her parenting time with her father like she tried to, it sends out a very clear moral and legal message to everyone that my daughter has 2 fully equal parents in her life, it reflects the reality of her life. In fact, she lives with me for approx. 35% of the year. She has 2 homes of equal value.
Yet, when it comes to other matters such as CSA or child-benefit, I am deemed the "Non-Resident Parent", which I highly object to in principle and also it is totally at odds with our parental legal status. Why is this so? Because my ex is in possession of the CB.
Now I cannot make a claim for a portion of the CB, and thus I am not eligible for a whole raft of other benefits that my ex is, despite me, arguably having MORE expenses than my ex, I provide a bedroom for her at mine, and there is the associated costs such as a larger house, mortgage etc etc.
my motivation for wishing a reform of CB is from a sense of fairness and how it reflects the reality of the parents lives, especially the shared residence order status.
... I know that HMRC can split CB - this can be under circumstances such as:
- if there are 2 children then one parent can claim CB for one child and the other parent can claim CB for the other child
- if the children are in a shared care arrangement that is easy to administer i.e. one week-on, one week-off then the CB can be split between the parents
those are the only circumstances I can think of off the top of my head. As I say, I think the whole system of CB is a bit out of date now, as it is actually quite discriminatory in it's effect and also is quite a clumsy way to administer benefits which could be done via the income tax system. But that is another argument for another day.
... I think you have to first work out your ex's motives, if it's from a feeling or system of control then I would be very wary.
Any agreement that has been made at Mediation is not legally binding, although it would be assumed that you have agreed to what is in the final mediation agreement. Not having read it or realised what was in it is a poor excuse because it is your responsibility to check everything and presumably you are eligible for legal aid so could have it checked out by a solicitor. You would have to argue that that is not what you really agreed to and you felt pressurised by the ex or the mediator didn't fully explain things to you (if that is what happened)
... just my tuppence worth