#1 Female member(s)
One way for The Undisputed Era to expand and distinguish itself upon moving up to the main roster would be to feature not only its core male members but also one or more female additions to the faction.
The group is grounded in its combination of technical expertise and its swagger. A veteran like Mickie James or Natalya could fit the bill.
A top AEW star just called one of his colleagues 'spoiled' and 'narcissistic' HERE.
Alternatively, if WWE wanted to keep the group stocked with fresher talent, they might consider temporarily moving Sara Del Rey out of her trainer role in developmental to finally work in a WWE ring, or call up a young heel like Lacey Evans.
As another angle, Roderick Strong is in real life married to Marina Shafir. As such, she’d be a natural enough choice to conscript into the group, conceivably bringing Horsewomen colleagues Shayna Baszler and Jessamyn Duke along with her to really blow up the group and see them dominate both the male and female ranks.