Four attached person were not children of Sir Erasmus and Frances: Susannah Dryden ; James Dryden ; Charles Dryden ; William Dryden Sr. .
As my families genealogist / archivist do agree with you about William {Dredden} Dryden NOT being the offspring of Erasmus Dryden. Everything I have been able to scrounge- acquire or find says that he is but the dates and places do not match. There is quite a distance between Canons Ashby, Northampton shire, England and [ Edinburgh] Musselburgh, Scotland where I first hear of William Dryden Sr. Now as for James, Charles and Susannah Dryden I have absolutely no knowledge as they do not fall into my direct linage and were not researched.