The Phoenix Force is just being used in Warsong as a plot device to resurrect the dead Stepfords. It has nothing to do with them or Emma. And it's a marketing device as well, since far more people are tricked into buying the series when it's called Phoenix:Warsong rather than a more accurate title - Stepford Cuckoos: Origins.
The sales figures show that's exactly what happened:
X-MEN: PHOENIX - WARSONG
09/06 #1 (of 5) - 73,503
10/06 #2 (of 5) - 54,727 (-25.5%)
Bit of a stiff drop for issue #2, and theres a common theme with the X-Men miniseries - this one turns out to have very, very little Phoenix content. Its actually an origin story for the Stepford Cuckoos. Itll be interesting to keep an eye on this one, to see whether people drift away when they realise what it is.
http://pwbeat.publishersweekly.com/blog/2006/11/28/marvel-month-to-month-sales-october-2006/