Shared techtree?

[Giho]

In my map I have four teams. Two of the teams are friends by a "friend" trigger. One of that team has only a hero and I want him to be able to train/buy units from the other "friend" team. I have given the building select hero and I added some units to sell. But when he tries to buy he cant because it says "require blacksmith". He doesnt have the same techtree what to do?
And when a "enemie" goes to the building they can buy units (not those units who require somthing like a blacksmith for example). I dont want that to be posibble. What to do?

 

[Pyromancer]

you could have a con.: unit type of triggering (bought, trained) equal to (then have a var that is set to the first hero of that type)

then the action is, remove triggering (do i have to say it again?) unit from the game, mabey give back sum gold, and have a message too.