You have a good point, Marion. But, when in doubt, go with the more credible option. I have provided a link to a summary of original sources, which names Millicent and the husband and father of John Tilletts.
In addition, now that her sister, Amelia Veale, has been substituted as John III mother, the error is clear. His date of birth is 1729, whereas hers is 1730. While birth dates of that era maybe wrong by a few years, Amelia cannot be the mother of John III unless you make him ten years younger and her ten years older, give or take two years.
Geni.com, however, has Millicent but only shows her second husband and no listing for any of the John Tilletts.
The summarized court case concerned a suit by John and George Tillett against Millicent's second husband, Job Carter (father of Peter, husband of Amelia Veale), over disposition of the will of their father, John Tillett.
Thus, even if we do not have original documents John and Millicent are more credible parents of John III who was born a year before Amelia, who has been added as his mother along with a George as the father of John III.