campaign, guard vs black templars vs speed freaks vs tau vs iron warriors

[HavenDan]

Well my friend is having a birthday celebration tommorow so we were thinking of playing a 5 way campaign!

Well heres the backstory (or what there is of it so far..)

The 101st Veadan Rifles are holding out against the ongoing numbers of WAAAGH Cirkitz on planet (insert name here). Nearly overrun, the Black Templars rush to the aid of the Veaden Rifles.

Misson:
Annihilate

1000 point speed freaks vs 500 pt guard and 500 pt black templars via deepstrike (come in as reserves, no vehicles)

Meanwhile, the Fallen (dark angels) make a temporary pact with the iron warriors. The iron warriors protect the Fallen from the hunters, the dark angels, in exchange for (something or other)

Misson:
Annihilate

500 pt iron warriors (includes fallen squad) vs 500 pt dark angels

Several hours later, a Tau vessel gets stuck in a warstorm and ends up above the planet (insert name here) The Tau are forced to make a landing in order to repair their ship. The Black Templars, seeing this, see this is an oppirtunity to purge some xenos! (random misson generator) Either stealth if they do it stealthy or recon if they do it unsteahtily, havent really worked out the details.

Well anyway, how can i improve this because i know this sucks