Shannon B. answered 08/19/19
Writing Tutor with Experience Teaching and Studying Writing in College
It can definitely be done. I have seen novels switch POV before, but be consistent with when you switch POV. I would recommend switch chapter to chapter. If you don't want the adult POV to have as much impact as the teen POV, then you could do little fragmented chapters. It's your series. Do it how it makes the most sense. But however you do it, be consistent.
Also make sure that the two perspectives merge at some point, that they're not mutually exclusive unrelated perspectives. The two characters - adult and teen - should be related or have something substantial in common, something to connect them. Otherwise you'll have readers asking what's with the random adult? If their relationship is immediately clear, cool beans. If it isn't, that's an opportunity for you to add in clues sporadically and then gradually have their merge make more sense.