Not trying to get too far out from the shore. I prefer facts. Gerald Porter apparently tried to reconstruct the ballad but I doubt he did it as well as you've done. Still, I'd like to see it.
Didn't know CFS was written by George Brown. It's good to know because I've listed CFS as an Appendix to Bramble.
The two early broadside I found are:
a. "The Merchant's Daughter and Constant Farmer's Son." Pitts broadside dated 1819-1844 with the imprint: "Pitts Printer and Toy Warehouse 6 Great St Andrew Street Seven Dials." b. "Merchant's Daughter, or Constant Farmer's Son." Broadside printed by Taylor, 16, Waterloo Road, near the Victoria Theatre, London c. 1830-1840 (imprint features a woodcut with three squares; the first is a drum, a bird of prey and a horse)
Is Brown's name attached to these broadsides? What date do you surmise? I put a date of circa 1830.
So if Brown wrote it based on Bramble then it's probable that his print shop had access to a copy of Bramble. Or he knew it from tradition.