Hey All,
This may be an inconsistent rule with the system, or it may hinge on the use of the word "Upgrade". So help me out.
STARTING DICE POOL
In the rules (page 19 EotE CRB), it states that to create the dice pool for whatever check is being made, you find the attribute and the skill, and compare the two. Whichever is higher, you use that as the base number of ability dice (green), and the lower number the number of upgrades. By doing this, you never need to worry about "upgrading" dice as per the Upgrading More Dice Than Available (page 21 EotE CRB).
UPGRADING
The rules (page 21 EotE CRB) state that when upgrading dice (I'm imaging after the initial dice pool), when you run out of dice to upgrade, you add an ability dice (green) then upgrade that to a yellow and so on. To explain graphically:

MINIONS
What happens here? The dice pool for these guys always remains static, and is "upgraded" the more that exist in a group. So graphically, is this what happens?

