Since there is a Half-Troll template in the Fiend Folio, I was wondering if that template could be used to make half breeds of the various Troll sub breeds? Such as the Crystalline, Cave, Forest, Mountain & War trolls found in the Monster Manual III? Or is there perhaps another template or set of templates I need to look at?

And if I did use the Half-Troll template, What would be a good and balanced way to show that this particular Half-Troll is descended from one of the sub breeds rather than a normal Troll?