I can't say for sure whether there is a connection or not, I haven't been able to spend too much time with the siblings of ancestors. I live in Australia and when I am able to get to the ERO in Chelmsford I usually have a list as long as your arm of possible ancestors or possible leads, so it doesn't leave much time for their siblings, other than finding their baptisms. The name William has been used in all generations of my line except the last two but then of course it's a pretty common name, so not too much emphasis can be placed on it.
After many years of fruitless search for my ancestor William Tibbel (Theobald) I finally found him in Chelmsford plus the marriage of his parents John Tibbles and Elizabeth French in 1774 at Chelmsford. As an aid to finding a John Tibbles/Theobald circa 1749 I'm noting any Theobald families in the hope that the children's names might suggest a link to my line and then hopefully give a lead to John. The info I have on some Theobald ancestor's siblings suggests that they were prone to ranging far and wide in Essex, so I'm keeping my options well open on the birthplace of John.
If you have the names etc of the two daughter and handy I would be grateful for them.
Thanks and regards.