It Never Works Out According To Plan — Yours, That Is!
And even when it does, it's only for a short time. Life after divorce is always changing and you won't have a lot of control over those changes. We often get hopelessly caught up in parenting plans when we first separate, and— while that is important— it doesn't usually prepare you for the on-going changes and negotiations that go on for years— changes that you don't always like but learn to live with. There is the on going trade-off of which battles will catch your children in the middle and when one must learn to lose a battle to win the war— or should I say the peace— the peace of mind your children need. Life takes twists and turns that will never be in the "plan" so you must learn to go with the flow or be hopelessly mired in your own anger or disappointments.

Parental Time (aka custody) And Shared Financial Responsibility (aka child support) Are NOT Tied Together
Though they might be tied together in the eyes of your mother or your mother-in-law, these are two separate issues. When you confuse them or make them cause-and-effect items, you do a squeeze on your kids. It seems like such a natural ("if he doesn't pay support on time, well then the kids just won't be ready on time or at all" or "I'll be damned if I'm going to send a check this month if she and her honey are going on a ski trip: a) with the kids (that's not what I'm sending support for and I'll not see them this weekend like I was supposed to) or b) without the kids (she's away and I have all these extra food bills this week with the kids here) but this is not a life situation where each month comes to an EVEN tally. EVEN it never is. Equitable is the best you can hope for. Marriage isn't EVEN so divorce sure ain't gonna be.