Restricting Stock to certain tracks Options

[Frascati]

Hi

Is there a way of restricting stock to appear only on certain tracks. I have some military stock which I wish to appear only on military sidings. By putting this stock on Industry tracks, Ive got it partly doing what I want. But it also appears in the random mix of stock that is used to fill the route.

Secondly is there way to influence the selection of stock. Say have the local operators stock predominate but have foreign stock occasionaly turn up. It seems that at the moment all boxcars (say) are put into a pool and treated equally so that if you had say 5 SP boxcars and 20 foreign, the SP cars would only appear 20% of the time.

Thanks