The most I could find of it comes from the bugtracker.
The emu's stacking groups are as follows:
Standard Buff
Morale Buff
Tactics
Exceptions (career mechanic-related buffs, Heaven's Blade, etc)
The rules within the groups are as follows:
Buff: Most powerful is used
Morale Buff: Most powerful is used
Tactics: All stack
Exceptions: All stack




