While the Greece/Byzantium situation isn't completely sorted out, I don't plan to artificially link them to Rome in any event-driven way. America isn't related in any special way to England as well, for example.
I think for America and England, both civs existed as distinctively separate nations for over 200 hundred years and throughout multiple important conflicts throughout history (Revolutionary War, WWI, WWII, and the Cold War most notably).
The Western Roman Empire (if you minus the years under the tetrarchy) on the other hand barely coexisted with the Eastern Roman Empire for over 100 years before it collapsed.
I do plan to shift Rome's ambitions more to the east, both AI and UHV wise, and maybe the conflict with Byzantium arises automatically once Rome owns Greece regularly. I won't include an extra difficult "complete Roman Empire" UHV though.
What about a combination of
-Making Romans get an even slightly higher production boost and/or decreasing cost of legions
-Including an easier-to-achieve "complete Roman Empire" UHV, for instance, only needing to control at least 1 city in France, 1 city in Spain, 1 city in Great Britain, 2 cities in Northern Africa, 2 cities in Asia, 2 cities in Balkans/Eastern Europe (Constantinople would count both as city in Asia and city in Balkans/Eastern Europe).
-Help out AI to emulate Roman Empire by having "total war"on Greece and Carthage, spawn some units in Levant, spawn a settler+defender in London and give an x% chance to flip cities around Mediterranean to Rome (if not human player controlled).
Is there also a way to make Spain, France, Balkans, Turkey, the Levant, Egypt, and North Africa all be considered part of one continent (for combat purposes) from 500BC to 200AD?
BTW, when are you planning to work on your combat update? This mod's looking amazing already, but I'm still really looking forward to revamping the combat system.