Since I have not personally looked at any of the Dutch records now available online and know that some of the genealogy in A SEARCH FOR POLLY was in error and names in universal early genealogy were usually spelled several ways I will still post what is said about Jan Marselis Van Bommel. Re your: "I note that Jan Marselis Van Bommel would be roughly a contemporary of Mathais Corenratsen son in law of Hendrick. Marselis. So the children would be of the same generation: both have a Sytje"
ASFP: "Another Marselis who preceeded PIETER VAN MARSELIS to America was Janse (son of Jan by patronymic name) Marcelis Van bonnel who arrived at New Amsterdam January 1664. He was reported to be a man of wealth in the New World in 1665--Janse was born at Bommel in Gelderland and was one of the first settlers in Beverwyck. He was married to Annatie Gerritae, and they are progenitors of the New York Marselis."
Munsell is quoted as saying: Marselis, Janse Van Bommel, "born at Bommel in Gelderland." One of the first settlers of Beverwyck and ancestor of those bearing the name Marselis in this region. Was farmer of the excise for several years following 1655. his wife was Annatie Gerritse. Ch: Gysbert; Huybertje, m. Joseph Yates; SYTJE, m. Joseph Van Staten (Zandt); Judith, m. Lucas Hooghberk;