I'm looking into using the CMS as DD's father isn't paying regular maintenance. I spent over a year being "understanding" about his situation and receiving next to nothing, he eventually got up to date with me with a promise it wouldn't happen again - it is.
Thing is he rents a house with his sister in law and her 3 kids (one of which is 18 now so not a kid). He has no responsibility towards these kids - financially or otherwise - but there doesn't seem to be a differentiation between kids you have some form of responsibility for (e.g. your partner's child) and ones you simply share a space with within the CMS calculation.
Can anyone shed any light on this?