I would stop into guest relations and see if you can change this around a bit - not to increase the number of FP+ but to see if you can spread them out more evenly between your family.
Even though your kids are old enough to ride alone not every kid old enough to ride alone could handle it - especially if there were a long delay or ride interruption and I am sure the CM would understand the situation.
Maybe instead of 3 FP for each kid they could reassign one per day to each parent? Then you could use one FP+ to ride together as a family of 4 and then finding one ride that your comfortable with them doing alone for the other- like alien swirl, barnstormer, tea cups, triceratops spin where you can see them the entire time.
IMHO it won't hurt to ask ….. alternately you could switch bands and accomplish almost the same thing but you would have to ride in groups of 2 instead of 4.