Belowmins:
The contact will be with AAWH and cover all certificates of the holding.
Look at the MESA or Republic Airways Holdings. Their single CBA states that all flying done by any certificate owned by the holding will be done by Pilots on the single seniority list.
Asked the ALPA lawyers. This is a much better solution than having two separate lists and CBAs owned by one holding company.
Example:
Trans States Holdings GoJet and Trans States Airlines. Playing one group against the other.