One Christine Hollis writes this on WikiTree:
"I have done quite a bit of research on the Hollis line in the past and it doesn't appear that Mary Groom is the same Mary that was married to John Hollis. I would rather not merge them unless we drop the whole Groom name."
https://www.wikitree.com/wiki/Groom-127
Therefore, I've added a question mark after "Groom". Does someone have compelling evidence that John Hollis's wife did in fact carry the name Groom?