Phillis was Thomas Rook's second wife as he was a widower when he married her. There is a record of someone with his name being married to an Elizabeth who died in 1797 in Newnham. I think he already had some children to this wife when he married Phillis: they may have been Anne, another Thomas (who is the Thomas from whom I descend).
Possibly also a Miriam. There was a Susannah Rook(e) too who is somehow related. The latter was a witness at my Thomas' wedding.