Youre grasping at straws here. Plus the child tax benefit has changed since the FCSG were introduced.
The bottom line on expenses is this: if it isnt necessary day care, medical over $100 a year or educational, she needs to get your permission first. If she is claiming things like pizza day or $10 school trips, its not extra ordinary.
Look at the items she is claiming and if you disagree you simply argue that she never sought your approval, the items do not pass the test of extra ordinary and you do not agree to them.