[Frederick_d_Ohlmann]

Pure race on each planet, and deport the Piundon on planet with an atm they can breath, so you have extra room in this planet (it will be no more domed). The piundan planet will be more angry but it's easy to counter with troop/ship/urban pacification center.
The only excpetion is if the piundan breath the same atm than you ; if this is the case, drop 1m of piundan in every planet so they will expand faster (due to approximation in growth calaculation the 1M piundan will make at least 1M of extra people evry turn)