Tier 1 Terriers have been "borrowing" kids from the Elite team and even from other teams for years. Regular season, playoffs, tournaments, whatever.
Know who else does that? Breakers. Every time you play the South Shore teams they have different kids.
Relax and get use to it. By the time they're midgets you'll see a roster is hardly a fixed roster. One weekend a kid will be on one team and the next he shows up on another. Relax I hope the kids had fun and let's leave it at that.