Here's another far-fetched suggestion.

If Charlotte was a spinster when, as Charlotte Chapman, she married Henry Corrin in 1830, then it's worth looking for a Chapman family on the island at the 1841 census.

There's only one Chapman family which has parents and siblings in the right age range. They're at Stanley Terrace, Onchan, an upmarket address going by many of the neighbours who are "independent" with servants.

Onchan District 2, page 5
George Chapman age 72 Independent, born Ireland
Mary Chapman age 57, born Ireland
Ann Mason age 17 Independent, born England
Mary Ann Chapman age 35 Independent, born Ireland
Helen Chapman age 30 Independent, born Ireland
Frances Chapman age 27 Independent, born Ireland
Ann Fell age 25 Servant, born IOM

Then next door-----

Christopher Hemsworth age 50 Independent
Charitie age 40
Sarah age 18
William age 16
Marmaduke age 14
Christopher age 12
Albert age 11
Elias age 9
Julia age 6
Frederick age 4 and a quarter.
All born Ireland, except the youngest,Frederick, who was born after the family had arrived on the IOM.

So, trying to work out why Charlotte and Henry named their 1836 child Julia, here's a theory, based on the possibility that Charlotte's father was George Chapman (and Mary was mother or step mother ). While Charlotte was pregnant in late 1835 / early 1836, she was visiting her parents in Douglas where she met the new next door neighbours who had a string of children including a small baby called Julia. Charlotte decided that if she gave birth to a daughter, Julia would be a lovely name.....

OK, fanciful twaddle. But it would be interesting to know if there's an MI for George Chapman.

CHAPMAN, George 84 Onc 18 Dec 1847