Hi Brian,
I'll try to find time to check the ballads you mention for earlier broadsides, but even if I can't find them that doesn't mean they didn't exist. Regarding the unsophisticated state of the people the ballads were collected from, the earlier generations or influences their predecessors had might well have been much more sophisticated. As for there being no broadsides found by Sharp, that doesn't mean their predecessors didn't have access to them. If they had them with them when they arrived or bought them on the east coast they would be unlikely to survive all the trials of migration.

When you write 'Earl Brand' do you mean Earl Brand or Douglas Tragedy. Child lumped them together but they are 2 distinct ballads, the latter a rewrite of the former in my opinion.