What I would recommend if you want to keep them, and help them grow as musicians? Challenge them to read along and sight read well enough like a bassist. Follow the chord progressions as just roots, just the tonic, as if they were bass players. Then let them power chord it as root + fifth. Then when they can play the song fairly well that way, challenge them to learn the proper finger position for a full chord in an easy spot they can "arrive" at in the piece; like a held whole note, or the opening chord, or the closing chord. Let them root along where it's challenging, power chord where it's easy, and play full chords where they have a second to find their fingers.
Is it the most OPTIMAL or PEDAGOGICAL approach? Absolutely not. But guitar is a little different of an instrument for most teens to sit down with. A lot of them will come from a non-pedagogical approach, and this will give them a solid reading foundation and a chance to safely explore challenging jazz chords. All of this without sacrificing their texture in your ensemble.