First let's actually define what elements are part of this motif. I would say that burial places are incidentals and that the motif proper includes a ROSE, a BRIER and a TRUE LOVER'S KNOT.

The Scots "variation" consists of two lovely floating verses that lack 2 of the 3 elements that define this motif. There is no ROSE and no TRUE LOVER'S KNOT. This disqualifies it from being identified as such. One out of three doesn't cut it. The Scots simply do not favor this ending. Perhaps they saw it as a subtle means for others to appropriate their ballads. They came up with their own which is quite charming IMO, but it is clearly a derivative of the other.

Bottom line: the Scots did not attach the ROSE-BRIER MOTIF to any of their ballads. Other people did that. Some of them might even have been Scots who have forgotten how Scottish they were. And that's fine. My favorite versions of Barbara Allen are the ones that came from the Appalachian tradition and they usually have it.

Once again, they either left it off, or tacked on their own. I'm not saying it shouldn't be there, I'm just saying it didn't start out there. Not at all. That's what I mean when I say "indigenous." It might be there now but in days the rose-brier motif was really making the rounds, no way.

To answer the question I'm trying to answer, you would really have to exclude the Scottish ballads. I also suspect that they may have come up with the alternate ending and attached it as a pre-preemptive measure, in order to prevent the rose-brier motif from being added to any of their ballads.

That leaves three: Earl Bran, Fair Margaret and Sweet William (I have included Lady Alice in this grouping as regards the motif) and Lord Lovel. But first, I will look at any Irish versions of any of these songs. Obviously, because of its connection to Lord Thomas and Fair Annett, we should look at that one first. If I see the motif, that will be no surprise, butI bet you anything I won't find an Irish remake of a Scottish ballad with that Scottish birk-brier ending...

Now look at some highlights of this Irish version of Lord Thomas and Fair Annett:

h. An Irish version, recited by Ellen Daily, Taunton, Massachusetts.

Come riddle me all at once.
Or the bonny brown girl.
He dressed himself up in a suit of fine clothes,
With merry men all in white;
And there was not a town that he rode through
But they took him to be a knight...

...To Lord Thomas's wedding I'll go.'
She dressed herself up in a suit of fine clothes,
With merry maids all in green;
And there was not a town that she rode through
But they took her to be a queen.

He took her by the lily-white hand,
And led her along the hall;
He handed her to the head of the table,
Among the ladies all...

...Then out spoke the bonny brown girl some words with spirit, saying:
'Where did you get the water so clear,
That washed your face so white?'
'There is a well in my father's yard
That is both clear and spring,
And if you were to live till the day you die
That doon you never shall see.'..

(the burial sites are missing in this one)

.......................................
.......................................
Out of Fair Ellen there grew a red rose,
And out of Lord Thomas there grew a sweet-briar.
They grew so tall, they sprung so broad,
They grew to a steeple top;
Twelve o'clock every night
They grew to a true lover's knot.

:-))) First plants are laughing, now having midnight rendezvous! There's yet another Irish version in Child's end-notes. The motif is there as well. Like I said, this is no surprise but where's the birk? Why do the Irish not favor the "birk-brier motif"? Why does that only come out of Scotland?

And of course a reminder that any ballad can become Irish or Scottish or what-have-you once they have worked it over and made it their own. Robert Winslow Gordon collected a "Kentucky Irish" version from Nellie Galt called "Milk White Steed" and the couple was buried in St. Patrick's church and the choir. But origins are another matter.

Jim, that's the Douglas Tragedy, a variant of St. Mary's Loch is an actual place and there was once a St. Mary's Kirk there also. The villian is the Black Douglas. 7:Earl Bran and 74:Fair Margaret and Sweet William have strong local traditions. One in the area near St. Mary's Loch and the other in Norfolk...