Question for those with shared care

Could people who have either their child or have partners with a child in shared care possibly share how they deal with the money side of the equation.
Current DD father has her 5 nights a fortnight so will be getting WFF and the child support that he pays goes from $250 to $88 a month. Is it reasonable that under those circumstances he should also be paying for a third of her daycare, swimming lessons etc?
What does everyone else do in similar circumstances? Do you have it in writing / have a parenting plan?
I have the parenting plan off the Justice Website http://www.justice.govt.nz/courts/family-court/documents/pdf-pamphlets/082_Parenting-Plan.pdf and was going to see about fillling it all in with him. I dont really want to get lawyers involved or anything and I dont want it to be all about money but Im just worried IFKWIM?
Thanks :)

My DD's dad only has her one afternoon (2.5hrs) and one overnight a week (24hrs) and he pays me child support but we still split all her extra expenses down the middle (including the cost of daycare). She does dancing through daycare and also I take her to swimming and we each pay half of those costs. He is also responsible for her clothes, food and toys when she is at his house. Even though she is under 6 and its free anyway our agreement says he is responsible for half her medical bills as well. The thinking behind our agreeement was that despite me mainly having custody she is jointly our responsibility so anything that falls outside of normal day to day costs(such as her swimming) should be shared by both of us as long as we have both agreed to her doing the activity before payment is asked for.

We have ours in writing as part of our child support agreement. We talked about what we each should pay for and I put it in writing and we both signed it. We both have a signed copy of the agreement. I did it as part of our child support agreement so I wrote in a bit about us reviewing the agreement every year on 1 April (start of the financial year) but we didn't bother this year.

Hope that helps.

I wrote it myself. No, its not a legal document in that a lawyer didn't prepare it but we have both signed it so at least it shows intention if we were to ever have an argument about the whole thing.