Sorry to hear about the delay in your knitting class.
A couple of recommendations for you: Perhaps having some pictures of how to hold the needles might help the girls. Also, sometimes a play-by-play in images of what the needle and yarn are supposed to do will help people, too. Well, some it well help--others not so much, but still might be worth a try.
And finally, since you can't have your meetings, I recommend giving the girls some homework. Specifically, see if you can find out what progress (if any) each girl has made. Then tell them specifically what they need to work on and where they can find information on that particular skill (as in, direct them to specific videos either here or on YouTube).
Hope you're back to teaching soon. It's lots of fun, isn't it? I've taught both groups and individuals how to knit and crochet (but not at the same time).