The modifier formula is fun, but it may not work well for all neutrals. How about this……
1. State the neutral you wish to negotiate with.
2. Pay $5 to roll 2d6 @ 10 or higher.
3. If failed, pay $5 and get a -1 modifier for each attempt afterward for the same neutral only.
4. If successful, the standing army immediately become your troops, without needing a NCM.
I think this is a good compromise between rolling craps and box cars.
Also… When attacking strict neutrals outright, only neutrals in the same block become pro-opponent. The 4 neutral blocks are:
1. South America
2. Europe (including middle east)
3. Africa (not including middle east)
4. Mongolia
Thoughts?