I was in Brisbane over the weekend and took the opportunity to buy two histories of the Albigensian Crusades and one of Simon de Montfort (junior).
Keep watching this site, I will be back with more information once I have digested this lot.
A quick look through the indexes and chapter headings confirmed that there were no obvious mentions of the Caldwell family name.
I suspect that if any "rellos" (Australian for relatives)were there at all they were probably with Simon de Montfort (senior) and the other "bad" guys.
I will have to have another look at the Albigensian Crusades myth to help me interpret these histories.

Tom