Oh hey, the child support tables have changed. I wonder if it's for better or worse.
Your CS for two kids 1594
Your CS for one kid 989
Her CS for two kids 597
Her CS for one kid 359
Anyways, it's a grey area when you have different kids on different access schedules. I don't know which method you used, but here are a couple.
Method one
It could be calculated that you take the amount for one kid that she would pay you for the older kid, and subtract your offset amount to her for the other shared kid.
She pays you 359, you pay her 989-359=630 for a total of $271 from you to her each month.
Method two
You could take the amount for two kids for each of you, divide it in half, and have her pay the full amount to you for one kid and do offset for the other.
She pays you 597/2 = 298.5 and you pay her 1594/2 - 597/2 = 797-298.5 = 498.5 for a total of $200 from you to her each month.
Method three
Or my personal favourite, which I think is fairest and wish was in use: You each put your table CS for both kids in a pool, and take out of the pool in proportion to the amount of time you each have the kids.
You put 1594 in and she puts in 597, for a total of 2191. You have 3/4 of the kids' time, so you get 3/4 of that or 1643.25 and she gets the remaining 547.75. That means you get more than you put in, and she gets less, so the difference is 597-547.25 = 49.25 OR 1643.25-1594 = 49.25. So she pays you $49.25 per month.
A search of CanLII might help you find what method is usually used, cause if you have to argue which one to use with her you know you're each going to go with the one that benefits you the most and end up in court with the one judges like to order. But for a difference of $300 a month between these three methods, is it worth court to you?