The puzzle appears to have been solved for those interested

After sorting through transcribed wills I now find that Issable Qualtrough als Shirlogue/Sherlock was the widow of Humphrey Qualtrough who died along with his/their daughter Issable in June 1720 in Rushen.

Humphery's will gives corroborating evidence that his daughter Catherine is in Ireland and you will see that Finlo Cretney is a witness to his will and also becomes co-executor.

Humphrey Qualtrough 1720
(jointly with his daughter, Issable Qualtrough, 1720)

(2 Wills in this - written in different handwriting )

Rushen 1720

The Last Will and Testament of Humphra Qualtrough
of KK Christ Rushen and Issable Qualtrough his Daughter
who departed this life about the eight of June 1720 being of
perfect mind and memory. First they committed their
soul to God and their Bodys to Christian Buriall.
Item.. he left sixpence legacie to his daughter Chatherine
Itm he left sixpence to any one of his friends that will
claim any right to his goods. Itm his daughter left a
mant and a peticoat to her sister Chatherin that lives in
Ireland, if she should come to the Island, if not that then
she left the mant and petticoat to her Brother's daughter
and she left a Sheep and a Lamb to John Corkish Daughter
Item she left all the rest of her goods to her mother
Itm .the said Humphra Qualtrough nominated, constitu-
ted and appointed his Loving wife to be Exetrix of all
the rest of his goods movable and immovable whatsoever.

The Extx being not able

to travel ffinlo Cretney

& Wm Christian are sworn

in her behalf and

are Pledges for her

Testes:
ffinlo Cretney }
Ann Harrison } Jurati

Probati est & Jurati ?d

Will have to accept at this point Frances' theory that Finlo was just being a very helpful neighbour.

Oh the joys and challenges of genealogy