I first learned Jeannie Robertson's version around 1958/9 in my school in Rutherglen (just outside Glasgow in Scotland): my English teacher Norman Buchan had tapes of Jeannie from Hamish Henderson and I was enthralled by her singing -- and fortunate enough to see her perform live on more than a few occasions.

I've been singing Son David ever since, and I thought I was singing the version I first heard, but much later I realised that it had evolved.
In some of the versions of Jeannie singing (recordings from School of Scottish Studies from Kist o Riches site), she excuses the blood as coming from 3 sources - horse, hawk, hound - before admitting to it being from the brother; she sometimes includes, but sometimes omits the 'bottomless boat' verse .
When I re-examined my own version, I realised that I had done some 'adjusting', probably to suit my notions of ballad format and patterning, so my final version comes out as this:-

O what's the blood that's on your sword,
My son David, O son David?
What's the blood that's on your sword?
Come, promise tell me true.

O that's the blood of my grey hound,
Hi, lady mother, ho, lady mother.
That's the blood of my grey hound
Because it widna be ruled by me.

O that blood it is ower RED... etc.

O that's the blood of my grey mare ...etc.

O that blood it is ower CLEAR ... etc.

O that's the blood of my brother John ... etc.

But I'll sail away in a bottomless boat,
In a bottomless boat, in a bottomless boat.
I'll sail away in a bottomless boat
And I'll ne'er come back again.

O but when will you come back again? ... etc.

When the sun and the moon meet in yon glen,
Hi, lady mother, ho, lady mother;
When the sun and the moon meet in yon glen
Then I'll come back again.

SO, my question is -- would my version best be described as merely 'differing slightly' from a previous recording, or as a recreation? (I now know why I must have made my changes, and I'm happy with them -- but, the point is that I didn't know it was happening over that time.)