Thanks, Q. I forgot to add that the four lines I gave were the entire song; it was sung only as a round. But folks have always liked to add on verses, if they like a tune, or if the words bring to mind an appropriate parody...I can see it happening- a mother teasing Rose,her 'old-maid' daughter, Rose, Rose, Rose, Rose, shall I ever see thee wed?" And then of course, the other two lines she had to adapt, to make sense!

I have done no serious research, and appreciate the bits you gave. I do believe that originally the four-line round was all there was. And the last line could well have been the one you gave from the Australian site, "And thou but stay."