Currently the feature is not available for allied units. I plan to make a submod that enables certain upgrading on allied units, and make tech / lord skills affect certain allied units.

Cannot make it applicable among any two races, because there are only five UI tabs right now.


Based on my lore understanding, here is the tentative plan for which allied units can be upgraded by player faction:


>> Bretonnia knights path:
Available to all human factions, high-elf, wood-elf, dwarf when allied.
Benefit from Empire tech / skills.

>> Empire & Kislev:
Have access to each other's upgrade path when allied, and tech / skills benefit mutually.

>> Dwarf upgrade path:
Available to Empire and Bretonnia.
Dwarf artillery benefit from Empire tech / skills.

>> Elves:
All three elves can access each other, and tech / skills benefit among them. (end time lore -- or maybe exclude dark elf from this?)

>> Ogre upgrade path:
Available to every faction. No tech / skills benefit though.

>> Vampire Count, Coast, Tomb kings:
Shall they be able to access each other?

>> Skaven & Norsca:
Available to Warrior of Chaos;
Benefit from Chaos tech / skills whenever applicable.


That is all I can think of right now.

Your thoughts / comments are greatly appreciated.