Does 'kinsman' equal 'in-law'? Richard SEAGER and James AGUTTER

[Gadget]

By the way Gadget, in all the hundreds of wills I've seen, I've never come across the term 'affines'.
Is it used in a particular way or place?

It is the correct term for in-laws and used generally but, more specifically, in Anthropology. I majored in Anthropology in my first degree.

Add -

affine noun
af·​fine | \a-ˈfīn,
ə-\
Definition of affine

(Entry 1 of 2)

: a relative by marriage : in-law

https://www.merriam-webster.com/dictionary/affine

[goldie61]

 I majored in Anthropology in my first degree.

That sounds a very interesting thing to study Gadget.
I expect quite useful in genealogy too.