Problem Factions/Rebels... A Solution??

[Magneto]

Here is the tutorial: Part 1 and Part 2

I have BI, but never played it, so I have to ask:
What makes the difference to have a named legion? That you just can recruit them in 1 Settlement - for example, Legio 6 in Segesta? That would throw the vanilla balancing completely away - Vanilla is balanced for 4 roman factions; rather bad, as Romans always take the maps quickly, but still. Having one Roman faction, which has recruitment limitations, Is just the other extreme - Rome would be wiped out like it is nothing.