It's important to note here that what they were calling Ballets and what we call Ballads are not necessarily the same thing. So, "Who Liveth so Merry" is not a ballad in our sense, and to be looking for ballads that match up with these titles may be fruitless. Ballett often just meant "broadside" and so these could be poems, prayers, political tracts in verse, etc.

BTW, Barry and Robin Dransfield actually did a recording of "Who Liveth So merry" on one of their early LPS. It's worth hearing.