Mixing is fine --- that's how most people usually switch over from breast/formula to regular milk. With my boys, I had to do both when they were really little -- and so sometimes they got boobie milk, sometimes they got formula -- and they did fine.
However, starting her off on half/half might be a bit much for her --- especially with all the iron in the formula. Maybe do 2oz formula to 6oz milk. I was lucky enough to have all my kids when the low-iron stuff was still available --- my kids were never able to tolerate the iron-fortified stuff. And, I found, that once they get a taste of formula, it doesn't take long at all for them to develope a preference for it.
So... keep that in mind & keep a good supply of Mylecon handy... and I think it'll be okay.
at 11:44 AM on Jul. 15, 2008