Hi - I'm assuming that Bob had looked at Daniel's marriage entry to Esther Christian and found that he was a widower, and therefore looked for a first marriage.
Perhaps he will confirm this.

Sorry, I couldn't find Jane in Maughold records. It isn't at all unusual to find children mentioned in wills who have been otherwise unknown (with no bapt) - or previously unknown aunts and uncles in a decree - which is one of the reasons that these are so useful.

Sue