I just saw this and I like the matrix idea and here's how we'll work it.
We will hash out a chart much like what Raptor put here. There will be 4 Categories.
Your standard fleet will be the left column
The ally you are bringing in will be the top row chart.
Based upon that you will have one of these 4 options in a particular verge spot.\
Trusted: Base Leadership Die roll for race
Untrusted: -1 to the Leadership Die roll for race, minimum 1 on the die roll
Desperate: As Untrusted but -1 to Leadership result ala the Ork LD rolls
Not Allowed: Nuff Said ^_^
and on the comment of the Radical Inquisitors, if it hadn't been about 2am when i saw that comment I was going to say that's PERFECTLY legit. That being said, this almost makes me want to add in the rules from what is it, Battlefleet Cadia for the reserve fleet chaos ships for the lower levels of this ally chart.