My son-in-law, and three of my sons, ran into that very same situation with their ex's. Other than going before a judge and requesting as has been suggested...YES!...the CP 'must' accommodate the NCP's vacation time, whether it conflicts with 'CP's' usual time or not! We are 'Michigan', and that's the way it turned out 'here' for those I mentioned. In otherwords, my sons' vacation times fell on some of CP's normal designated time, CP's were given 'no choice' but to forfeit 'their' weekends that fell within NCP's vacation time. And, then CP's hollered, 'well, then I should have some makeup time as compensation'. Judge told the CP's...'NO', it IS the way it is, THE END, PERIOD!
P.S.; Oh...and a couple of the CP's did in fact claim that some of the NCP's vacation conflicted with CP's pre-planned and important agenda which was to include the children. Judge told the CP's, 'that's unfortunate but...'!