I realise I'm a couple of years behind the times but perhaps this might be of help to someone.

I'm cataloguing Stanley's song at the moment for the Kist o Riches / Tobar an Dualchais project and came here looking for clues. Alas it's a singular entry in Roud and I can find little other trace.

Here are the lyrics from the 1974 tape I'm working on:
^^
And dae ye see love, yon flock o sheep
One hundred must I own but two or three
I'll grant them aa tae my moorlove Muggie
Gin she consents for tae gang wi me         [if, go]

Tae gie consent love I daurna gie          [to give, I dare not give]
Tae herd yer sheep high in yon heathery hills
I'll grant them aa tae my moorlove Muggie
Gin she consents for tae gang wi me

And dae ye see love yon herd o kye          [cattle]
One hundred must I own but two or three
I'll grant them aa tae my moorlove Muggie
Gin she consents for tae gang wi me

Tae gie consent love, I daurna gie
Tae herd yer sheep high in yon heathery hills
T'll grant them aa tae my moorlove Muggie
Gin she consents for tae gang wi me

And dae ye see yon ships at sea
One hundred must I own but two or three
I'll grant them aa tae my moorlove Muggie
Gin she consents for tae gang wi me

Tae gie consent love I daurna gie
Tae herd yer sheep high in yon heathery hills
I'll grant them aa tae my moorlove Muggie
Gin she consents for tae gang wi me

Fairly repetitive on the face of it, but Stanley manages to make it sound fabulous.

VOP's title is, in my view, incorrect. Stanley is clearly singing 'Moorlove' rather than 'Moorlough'. And while VOP has chosen 'Maggie', on the 1974 tape Stanley explains quite deliberately that he sings 'Muggie', and not 'Maggie', such is the pronunciation from his part of the world. He also says he got the song from his Auntie Maggie (McQueen, presumably, going by Stanley's own genealogical chart).

I think it's probably a verging-on-mondegreen conflation that, thanks to the well-known Irish song, 'Moorlough Mary', we find 'Moorlough Maggie' on VOP.

As for the song's origin / relationships, it's quite hard to say. There are any number of songs out there with the "I'll give you sheep and cows and ships on the ocean if you'll go with me" element. I can't see a great deal of similarity to 'Moorlough Mary' from the versions I have to hand in O'Lochlainn and O Boyle.

It reminds me a bit, in feel at least, of Roud 3785 'Cauries and Kye', or 'Courting Among the Kye', as Ord calls it. However, 'Moorlove' is so lacking in any kind of developed narrative, it's hard to link it decisively to anything else. One could venture it has elements of a handful of Child ballads (e.g. the latter sections of Child 228 - Glasgow Peggie), but the link is not strong enough to conclude that 'Moorlove' is a variant of any of them. It seems almost like a fragment that's been turned into a song of sorts through the use of formulaic repetition. Definitely a fragment of something, but not enough there to tell quite what at the moment.