I'm debating with myself if I should include it my main worldwide collection or separate it out.
Not sure what you mean by that, perhaps an aerogramme collector?
For me, I include these mutilated stationery pieces, "back of book"
on personal pages. (Country specific)
I find they add flavour.
I have them (aerogramme fragments for GB, South Africa, India, Yugoslavia etc & etc.
Go with what you feel is best.