You can do this by making a macro to set the raid symbol to skull and party1 sets it to his focus. Another to set symbol to square and party2 sets it to his focus.

Then to target the skull have a macro that on party1 targets focus. Everyone else does a /target party1.

For your dps macros use /cast [target=target,harm][target=targettarget,harm] spell

It's kind of a work around but it should work. It also ties up your focus but you could just use the player's name for that instead.