can't help you with the Brantls, unfortunately. Just wanted to remind you (but you probably know about this anyway) of the many different spellings of that name. During my own research on our Lower-Austrian Brandls I've found a g-g-g-g-grandfather recently who's name was written as Prantl or Praentl (a with umlaut, pronounced like e in elementary).
May I also suggest to post this same query over at the Brandl query board http://genconnect.rootsweb.com/gc/surnames/b/r/BRANDL/querie...
where there are chances that somebody might pop in and know more.