Hi Danae

After reading the article on Maria Cowley looked at 1871/1881 census :
1871 Conchan (Onchan)

John Cowley 38
Maria Cowley 47
Richard Cowley son 14
John Cowley son 12
Margaret Callister MIL 69
Louisa Quine step dau 12

1881 Onchan

John Cowley 48
Maria Cowley 55
Margaret Callister MIL 77
Louisa m Quine SD 22

So as Maria's mother Margaret Callister was with her in 1871, it would be a good reason why her father would not be wanted in the same house.

The will of John Crellin is an unusual one , very pointed that his son-in-law should not be near his daughter. There is no doubt it is the will of Margaret's father.

My email address is on my IOMFHS profile , if you email me I will send a copy of the will to you

Cheers
David