Yes Dippy, but it all comes down to conflict between the parents over the child doesn't it? If the PWC is using the CSA as a stick to beat the NRP then it's pretty crap parenting. If people could just accept that once you make a baby together, you are taking on a commitment for at least 18 years, regardless of whether you remain as a couple or not, then there wouldnt be a problem.
A PWC who tries to screw the NRP is as bad as a parent who fucks off and tries to avoid any responsibility. It's just another form of screwing the tax payer.