I'm more forgiving of the Knoll book now. Its possible that its only mistake here is that it combined the mother and daughter. Maybe Susannah Wait married Moses Barber after all.
Page 322 of this Rhode Island Historical Magazine shows her marrying Moses Barber.
https://archive.org/details/rhodeislandhistov5turn/page/n8
Is that true? It seems like there are more sources that prefer Susannah West as Moses' wife.
On FamilySearch Susannah West (LTVZ-WRJ) is married to Moses and she has a couple of interesting notes.
- "The number in the Mayflower Descendant is 37,373 for Susanna West Barber."
- "Susannah WEST ! BIRTH-MARRIAGE-DEATH: from FGS prepared by Mormon Pioneer Genealogy Society, 1983 (gives sources as Soule and Terry, "George Soule of the Mayflower", in Mayflower Families Through Five Generations, v. 3 (1980), pp. 1-39; Hubert Kinney Shaw, Families of the Pilgrims (1956), pp. 137-44; Records of J. Grant Stevenson, Sanford Porter Family genealogist) - says Susannah m. 24 Mar 1692, Moses Barber."
-- "The choice of West appears to be based mainly upon Samuel West's Memorandum Book described in "The Mayflower Descendant" 26:10. In an entry bearing the date 23 Aug 1802 Samuel West states that from the family records of his uncle Francis West he got the following information on his ancestors: His (Samuel's) great grandfather Francis West married a daughter of George Soule and had children listed by name including a daughter Susannah who married a Barber. The author knows of no evidence which discredits this memorandum book, and personally feels that West is the correct name."
The record for Moses Barber has several 'Waite vs West' discussions and West won.
https://www.familysearch.org/tree/person/collaborate/LTFK-P6P
However, one of the sources on his profile is a garbled marriage record showing Barber marrying Susannah Wault in Kingstown on 20 Mar 1691. Unfortunately the scan images are so terrible that I'm unable to find the original record. It seems likely that's supposed to be Wait, not West. It could be a different Barber but he doesn't seem to have any brothers.
https://www.familysearch.org/ark:/61903/1:1:F8KV-7DQ