"I think the system is wrong there, I think only dc the nrp has parental responsibility for should be counted." Actually I'd take it a step further and say that maintenance should not be reduced even if nrp goes on to have more DC. Their older DC don't suddenly not need fed, clothed etc because their nrp has more DC.
Back in the 90's it used to be the case that nrps partners income was ALSO included for calculations in how much maintenance should be paid, and maintenance was reduced if rp moved in with someone new - rightfully that was stopped as step parents are not financially or legally responsible for step children.
Lifebegins50 (god I hope you're right!😂) - is right that in addition RP's are ALSO the ones who's earning potential is restricted AND has high costs for childcare if working. When dd was younger I was working full time, slightly better that nmw so not eligible for hb, but low enough income I got child tax credits and childcare tax credits. The last time I can remember not worrying about money was when married, living overseas in a country with a lower cost of living, working in a job where the wage was good even for a British wage. Lasted less than 5 years that. Yes it's partly arguably choice as I met my ex who was army and chose to be a trailing spouse but that usually meant taking whatever nmw type job was available before dd and then being a sahm after having dd. I've said elsewhere on mn, not sure if I have on this thread, that I very much regret that, I was persuaded by ex, in-laws, my family and friends (who were also army wives and sahm at that time mostly)
"When he is older he is likely to truly appreciate how life was for his mum and he may judge you for building pots of cash whilst he and his mum struggled." So true. Dd certainly the last time she saw her dad and seeing stuff on Facebook (via grandparents) rails at the fact he always begrudged paying maintenance or even getting her decent Christmas/birthday presents when his subsequent children were furnished with designer clothing, latest gadgets, holidays and days out - things I simply couldn't afford. Last time he pled poverty re her wanting to go down and see him, he and wife 2 had just bought a 4 bed detached house with enclosed front and back gardens and double garage in the south east, they both drive cars no older than 2 years ever, even though he lives walking distance to work, they also both have latest gadgets and of course enjoy the same holidays etc with the DC. He belongs to a good gym too. And I know I'm getting get some bright spark saying "well if he'd just bought X y Z money probably was tight" - well he bought/paid out for all those things KNOWING He wasn't paying the maintenance he was supposed to and clearly not even setting it aside to give dd when older. Dd is lucky if she gets a card for her birthday these days - usually stepmums or grans handwriting at that. Ultimately it's not really about the money it's about the fact this demonstrates that her dad doesn't even think about her, doesn't miss her. It's utterly heartbreaking to witness.
I think it unlikely a 12-year old is fully aware of all his mother does for him with her being the RP. The things you mention are top of the iceberg in all that needs to be done to run a household let alone raise a child eg who do you think taught your son to cook? My dd a good cook but it was me painstakingly showing her the skills and praising the initially lacklustre (or highly spiced!) results to give her confidence. And at 12 he will be doing more for himself - that's what parents do - teach children to become self sufficient adults. I'll bet he's not sorting the budget, making sure bills are paid, keeping paperwork straight, meal planning, buying groceries, buying his own clothes, hoovering, dusting, washing dishes, doing minor household repairs, mopping floors,
Cleaning counters, washing soft furnishings, doing the general day to day tidying... He certainly wouldn't have done it when he was younger!
Also consider the audience YOUR parents, not unusual for children that age to say what they think people want them to say, whether or not the conversation was led.
Sue51 - exactly nrps and their supporters always happy to criticise but NEVER want to take on the role themselves - see it repeatedly on mn!