I'm up to 5 myself. My 02 WRX wagon My 91 Legacy SS (but strongly considering selling) My wife's 2011 Forester My daughter's 96 Impreza 2-door My 98 OBS (for sale very soon) But that's only the ones I have registered or titled. I have two more in states of repair I'll be selling soon too. It becomes an addiction.
Congrats on the growing family! Were stuck on two for the moment 05 STi, 09 forester and unless subaru comes out with a full size truck this month I'm guessing our next one may not be for a few more years.