Depends what expenses your c6 expects you to take care of
Best thing is to get your c6 to consent to being responsible for all children's expenses which normally only goes up and never becomes less
What we do is... My c6 keeps 25% for paying income tax and daily spending on lunch and traveling. The rest goes to the family fund. All family expenses like mortgage utilities school fees. Medical costs food ... All comes out from this fund.
If there is money leftover at end of year can use that for trips