Hello. I honestly don't know how you would create Facebook group other than to link them to your personal account (this is what I have; it's secret as well). I suppose you could create an additional Facebook account for yourself and create the group through that?
Each of my parents (& grandparents and aunts and uncles!) love it! They all check it all throughout the day. I particularly like it for when a little one has had a rough morning drop off or just is a little off...the parents can be relieved by seeing the child is happy and playing.
I even sign on new families (that have submitted signed contracts, of course); this gets them familiar with the other families and the daycare flow.
I post daily; little picture snapshots of their day and little funny happenings.
Monthly; I post a newsletter.
My Facebook page has completely replaced all the print material that I used to send home.