Hi Marian,
I have tried to "map out" all the Childs of Melbury Osmond but haven't had much success in linking them together but believe most to be related somehow! I see Grace as the daughter of William and Ann, along with 8 (or 10) other siblings. Have you seen the Dorset OPC online? They have births, marriages and burials for Melbury Osmond as well as the 1801 census, which William and Ann are in. I've found it really helpful. If you want the web address let me know I can send it, or just type in Dorset Online Parish Clerks into your browser and you should find it easily.
I can't find a marriage for William and Ann so they must have married in another parish, perhaps Ann was from elsewhere? I wonder if William might be connected to my Samuel as their children were born around the same time but I don't know. They are a confusing lot!
If you find out more I'd be interested to hear about it as I'm keen to piece them all together. According to an English relative of mine, the parish clerk at Melbury Osmond mentioned that there were about 2 early Childs families that came to the village so you might assume a connection between them all.
Best of luck,
Kelly.