Jumping ahead I know, but Big 10 numbers.
ND: 6 familiar foes in Big 10
Pitt: 4 familiar foes in Big 10
Syracuse: 3 familiar foes in Big 10
West Virginia: 3 familiar foes in Big 10
Navy: 3 familiar foes in Big 10 (most schools count the academies as P5)
Army: 2 familiar foes
Boston College: 2
Iowa State: 3

I'll stick with my 18 team leagues and take four: I'll take ND, Pitt, Syracuse, Iowa State. ND makes a push to include Navy but Navy isn't quite ready to face Big 10 competition.

East:Penn St, Rutgers, Pitt, Syracuse, Maryland, Purdue
Central:ND, Michigan State, Michigan, Ohio State, Indiana, Illinois
West: Northwestern, Minnesota, Iowa, Iowa State, Nebraska, Wisconsin

After this I went to the PAC:
Teams that meet criteria (include G5 because that was the most common for PAC):
Idaho: 5
SJSU: 3
SDSU: 2
NM: 3
UTEP: 3
NMSU: 2
BYU: 3
Wyoming: 3
Col St.:3

Based on the rules, PAC should not expand. However, I did not include Texas/Tech/TCU in my original claim for the SEC, so those three could move to the PAC. If I take from this list, however, I'm taking: SDSU, NM, BYU, and Colorado State to get to 16.

ACC:
(down Clemson and UNC to the SEC, Syracuse and Pitt to the Big 10):
5 schools meet criteria:
ECU: 2
Army: 2
West Virginia: 4
Navy: 4
USM: 2

Edit: WVU and Navy I'll take to get to 12. ECU replaces UNC and Navy gets the league back into NY after the loss of Syracuse.