I stumbled upon this puzzle on one of the cards in the book Day of Doom which hints that the Tomas branch would destroy the Madrigals. What is more interesting is that the message seems to be between two non-Tomas individuals.
Now, I'm not even sure if these two individuals are part of any of the Cahill branches or just members of another group of people who wants to eradicate the Cahills. If the latter is true, they could be just using the branches to go on each other by feeding the branches with wrong info.
If they are Cahills, why would they want to start another war within the family?
If they aren't Cahills, what have the Cahills done to them to do such a thing?