Sorry, Karen-- I don't have any experience using coir indoors with seedlings or cuttings. So far, I've only used it in outdoor containers and Earth Boxes, and I've used it without any additives (other than fertilizer, of course). Hopefully someone else can weigh in here to help you.
If I was going to try to adjust this for better drainage, I'd probably add about 1/4 to 1/3 perlite.
Keep us posted on your progress, please.
