re: synergy
i'm a bit confused by your question. synergy is a program that will allow you to move your mouse from one screen to another, across computers, allowing you to click buttons and have keyboard input, to the other machines. it is not a broadcaster.

keyclone is the broadcaster that allows you to coordinate your clones. and yes, you can run a single clone per machine adding it to that machines keyclone... then link all the keyclones together.

so when you hit a key in one clone, it will pass up to the local keyclone, then out to the other connected keyclones, and down into their associated clones. (there is no limit on the number of keyclones you can link together)