I am very familiar with the Hillmorton Parish Registers, as I am the one who set up that parish on Wikitree and added all of the extant early registers. I just added links to the baptismal registers for all of the children except Abraham and Henry. I checked every year for them (within reason), and neither their births nor their deaths are contained in the Registers. These registers are very complete for the years covered, so I believe that if they are not there, they didn't exist. John arrived in America with 5 children, and all of them have been accounted for without Abraham or Henry.
On John's profile, I separated Abraham and Henry from the proven children. As they have no other links, I'm not sure that they would be added back except that the "documentation" for them is an online tree, which might just regrow branches. Perhaps leaving them attached, with a note that they probably didn't exist, would be best.
