Marik Aeris:
I actually like this, but I would also make it so that allies/cousins can't promote to cohorts (perhaps with the exception of those allies/cousins already in game since it's a new rule).
So cohorts could be either new or promoted assistants while allies/cousins have to be promoted from assistants.
Overnight, I had, more or less, come to the same position. How about ...
Entourage-Assistants - always new L1.
Entourage-Cousins - always promoted assistants (Reward for long service etc)
Entourage-Allies - Could be promoted assistant or could be brand-new BUT with a link (as in the case of Lutz)
Minor-Cohort - Promoted assistant or could be brand-new
Cohort - Promoted assistant or could be brand-new
No more than one level (automatic) advancement at any promotion. NO L2 Entourage-assistant to L5 Cohort - But L4 Entourage-assistant to L5 Cohort would be OK.
Cousins and Allies both bring 1bp of investment with them.
Entourage-Cousins (effectively) buy their way into the family with a 1BP investment. Then their money becomes part of the 'Family Money', but the head of the Family (the PC) is expected to look after them.
Entourage-Allies, however, are different. It is more of a business arrangement. In that there is something in it for both parties. So far, I have given Entourages a loan from an NPC organisation (ie Clan, Church, whatever they represent) I quite like the idea of the ally bringing 3bp with them - 1bp from their savings, 1bp as an interest free loan from their clan etc, and 1bp interest free loan from the PC.
Cohorts and Minor Cohorts don't bring any BPs with them - BUT they do expect to be treated somewhere between the other two? If you are building a legacy for your family and descendants, they expect to be able to do the same thing (on a much smaller scale) for their families.
Don't forget that Cohorts (and even entourage-assistants) can be adopted as 'cousins' anyway. They don't get any extra status, nor any of the Entourage-Cousin benefits, BUT they add to your growing Noble Family.
For example: Rikka (who is Henry's Cohort) has been adopted as a cousin, and is now an adopted member of the family. Henry trusts her (she is treasurer of Midmarch) and she trusts Henry to look after her, and any children she might have. She is probably due for a 'House' of her own in Tusk soon. Tib, adopted as an entourage cousin, got (some of) his reward last kingdom round