Just trying to get an outside view.
A and B used to be married. They split up six and a half years ago, when their DD was 1.5 yrs old. Since they split up, DD has spent 3 nights with A and 4 nights with B. Both A & B consider B to be the residential parent, as B remained in the family home and A moved in with parents. A has always given B 25% of take home pay.
About 4 years ago A met C, and became romantically involved. A & C moved in together 3 years ago, and got married 2.5 years ago. C is a much higher earner than A, and so A’s lifestyle changed. Since then, A has also started paying for all DD’s shoes, school uniform, school trips and also ballet lessons. DD also has a room at A&C’s house with toys etc there, although toys tend to move between houses.
A&C are now married and have joint finances – shared bank account etc. A conversation is currently happening about whether this means B should receive 25% of A’s pay or more, perhaps 25% of A&C’s household income. C does earn more than double A&B’s income combined, and because so much money is going into the joint account, B feels that A could very easily afford to give more and finds it slightly galling that B often struggles with bills etc while A is able to take regular holidays/drives a new car/give DD extravagant presents. C is uncomfortable with taking on this level of parental responsibility for DD when DD is not C’s own child and would prefer to only help on an ad hoc basis. C is also worried that increasing A’s contributions would significantly damage A&C’s relationship by giving A no financial independence/limited financial input into the household.
(Sorry if this is mysterious. Genuinely don’t know if I’m being U, and wanted to keep it bland and dispassionate so people would tell me if I was)