Help with Partner's ex / the mother of

[Thenewpartner22]

Hi!

I have been with my partner and his children who he has part time for 2 years now. I have always gotten along with the mother of his children after getting to know her in a very friendly way. They seperated in a very civil manor snd have always gone through a private agreement with child support. 

There has been an estimate given that is slightly higher than the current arrangement which has been $A the whole way through (which is very substansial). She is now demanding more money based off the estimate however out of good will and for his family when the estimate given by child support was signifantly lower (1/4 of) he payed the higher amount regardless meaning she was geeting 4 times the amount if they were to go through child support. 

Obviously he is quite upset and frustrated at her in this siutation for approaching this the way she has not keeping in mind the past over payments. I would hate for things to turn nasty between them or he somehow lose out on this arrangement despite him doing the better thing the whole time.

Any advice on any of how to handle or apporach this as his partner? Its not a nice situation to be in feeling so helpless.

[Geotech]

Separation/divorce, child custody arrangements and payments are very complex and individual to each family.
It is admirable that you have made an effort to be courteous, and create an amicable relationship with the mother of his children. It sounds as though he was trying to financially support his children, as best he could.
You should not involve yourself at any stage with having any opinion, or influence over monetary decisions involving his children.
I assume, since he is paying the mother of his children larger sums of child support (than determined by the Child support calculator) that he can afford it on his current income.
The calculator is a gross underestimate of what it takes to raise a child, in a joint parenting arrangement (or not).
I also assume, that you are aware of the mother of his children's income as well.
You do not know what expenditures she spends on these children/that are required for his children in each household. It will also vary, as they grow into adolescents.
The manner in which these children were to be raised was determined long before you entered into a relationship with their father.
You do not know what conversations he has had/continues to have, with the mother of his children, when you are not present.
There is a multitude of financial facets that they are both responsible for delivering (in addition to basic household costs). Schooling, camps, extra curricula activities, health care, dental/Orthodontics, Optometry, tutoring, birthdays, Christmas, recreational activities and equipment,
driving lessons, private health insurance, musical instruments/lessons,
School holiday programs or holidays, IT equipment, family pets, counselling services or psychological support for the children, tertiary education in the future. Etc, etc..
It is endless, and specific to the age and developmental needs of each child.
The costs will increase as they continue to grow.

He has the option of seeking legal advice or mediation (as she may have already done), if he thinks this is necessary.
Either way, it has nothing to do with you.