Yes, it’s hard work and lots of individuals related to one another!
Like you, I was surprised at the wording of a child unyet unborn who could inherit. His late wife Elizabeth is (I think) the mother of the children he mentions. She was the sister of Levett Blackbourne (mentioned in the section about his daughters, although there are two Mr Blackbournes discussed there). Levett’s will also includes substantial legacies to his nephew, Charles and Elizabeth’s son Francis Chaplin. It’s in the same collection of PCC wills.
His son Charles appears to have been provided for by a Mr. Wells.
I have also skimmed rather, but the estates he mentions are in the parishes of Saltfleetby, Burgh in the Marsh, Wrangle and Skirbeck. All are to be sold, but Charles Chaplin of Blankney, (Chaplin = Chaplain?) Thomas Manners Sutton of Lincolns Inn and Thomas Chaplin will receive the personal estate associated with these four real estates, once some smaller legacies are paid. The references to estates on p3 look as if they’re referring back to the estates “hereintofor directed to be sold as aforesaid”.
Is the family mentioned in Burke’s Peerage?