I agree that the age range for Youth Olympics has been too tight. Even for singles skaters (and solo participants in other sports), I believe there was only a 2- or 3- year window, which meant that some athletes would be too young for the upcoming Youth Olympics, too young for the Olympics two years later, and then too old for the following Youth Olympics 4 years later.
A four-year age window makes much more sense.
This is the latest official information about ages I can find:
I'm not sure how that aligns with ISU age rules. The ISU likely would have input on age rules for figure skating disciplines, which might be somewhat different from those used for other sports and also from limits for regular ISU-sponsored junior competitions.
This site doesn't mention a lower age limit. Other sources I could find said 15-17 or 15-18. It seems the restrictions would be based on the athlete's age as of the Youth Olympic dates, not the July 1 cutoff the ISU uses or the January 1 cutoff for some other sports.
So I think there will be at least a three-year age window.
Four years would be better for the reasons I mentioned above.
I hope this will be clarified soon.
For federations that have at least one large existing junior synchro team that competes internationally, they may have to designate members who can be part of the Youth Olympic team vs. those who are not eligible for that event but can participate in ISU events.
Federations that have multiple existing junior teams that compete internationally could take the same approach and choose the best of those teams or the international team that best meets the YOG age limits to represent them.
Or those federations could form a Youth Olympic team that skaters would need to try out for and be selected for, that would then practice together for the Youth Olympics but might or might not enter ISU events that season. The skaters might have to take a year off from their regular teams as needed to practice with the YOG team.
Federations that only have one team with a wide age range and few substitutes would be out of luck.