Ok, let me try and explain since I think I'm probably the biggest user of hotstrings.

Unless you want to send the SAME key to each client, you need at least two hotstring files. The simple form of this how i'm using it now to pass ctrl ans shift modifiers, I haven't done any alt modifiers this round, but I have in the past using these same techniques.

Using 1 hotstring file for all clients to pass modifiers..

Hostrings
Ctrl-Shift-A -> CSASent
Ctrl-Shift-B -> CSBSent

Load your games and load this keymap for all of them adn when you press ctrl-shift-a it will send it and receive it on all clients.

Once you add come complexity to it, you can get even more creative...

HotStrings_Client1
A -> Client_PressedA_NowPressB
B -> Client_PressedB_NowPressA
C -> Client_PressedC_NowPressQ

HotStrings_Client2
B -> Client_PressedA_NowPressB
A -> Client_PressedB_NowPressA

Hotstrings_Client3
Q -> Client_PressedC_NowPressQ

Launch three copys of WoW or notepad even... associate hotstrings client 1 to the first one, and 2 to the 2nd... 3 to the 3rd...

Press A on client1 and B appears on client 2. If you go to client B and press B, an A will appear on client one. If you go to the third client and press A, an A will be sent to all three clients. This is because there is no hotstring associated with the client sending... On the first client pressing C sends a Q to client 3 and nothing to client 2.

The last part of this is where it gets confusing, but just remember KeyClone has no sense of "main", it just sends keys or hotstrings from whatever client you are focusing on at the moment... Just know that if a hotstring exists on the sending client, it will be processed only on clients that have matching hotstring names.