well i do hav an idea, it involves triggers tho..
EVENT:
A unit finishes an upgrade
CONDITIONS:
(Researched tech-type) Equal to Iron Forged Swords
ACTIONS:
Player Group - Pick every play in (All allies of (Owner of (Researching unit))) and do (Player - Set the current research level of Iron Forged Swords to 1 for (Picked plyaer))
You can try that, but u'd hav to do that for ea. upgrade. Tell me if it doesn't work...