In 1891, there is a Jane Harker, wife in Douglas
age 30 with 2 children Minnie 7, and Amy 5.
There is also a Florence harker a nusing child 7 months in Douglas with William and Jane Callow.
In 1901 Florence is back home with Jane as is husband Albert 46 a retired letter press printer. They also have a son Arthur 5.
There are burial records for Albert and Arthur.
Brian also has a marriage of George Harker to Lavinia Knowles on October 17 1892 in Douglas.

I had assumed that this was not the same George that married Elizabeth but, given the rarity of the name on the IOM, it is possible.
Finally Brian has a burial record for Eliza Jane Harker age 87 on January 13 1946. This gives an approximate DOB of 1868/1869. I found no matching Liza Harker in the census.
It would be worth checking her maiden name.