A129 addendum: In 3.5, turning swarms is actually easier than turning normal creatures (the swarm counts as only having half HD). I would recommend bringing that ruling to PF. Of course, turning in PF doesn't work off HD, so you would have a bit more work to do for a conversion. One way to represent this ease might be to treat the undead swarm as if it had a number of "pseudo-negative levels" equal to half its HD, then recalculate its will save to avoid being turned or commanded accordingly.