Marshall, from a gamer's perspective, it's important to keep Prussia and Austria from fighting each other. However, from a historical perspective, they didn't exactly get along all that well. True there were no major conflicts between them, but they each sure didn't mind when France brought them down a peg or two (or 10, in Prussia's case).
Gamewise, historicity and playability are worlds apart, at least in typical scenarios. Historically, France and Austria from 1805 - early 1812 were at war with Austria only twice, and then only for a couple of months at a time. Prussia did not join them in either war (although Russia did).
Prussia likewise was only at war ONCE (1806). Russia was ostensibly their ally early on, but Austria was still licking its wounds.
The era of grand coalitions didn't really get going until 1812. In the game, grand coalitions with human players start maybe as late as 1806, and then only if France is content to gobble up minor neutrals.
You might want to consider using different AI parameters in a single-human game from those you would use in a multi-human game that just happens to have one of them being run by the AI. Or, at least allow it as an option.
At LAST! The greatest campaign board game of all time is finally available for the PC. Can my old heart stand the strain?