Okay, I posted this over on the BF board, but not sure it was the right place or how many people may respond....anyway...
Is it okay to mix pumped bm and formula in the same bottle?? And if I do how much of each should I do (ie if DD usually takes 6ozs BM can I give her 4 ozs BM and 2 Formula??)

Re: Supplementing with Formula??
Yes. I'm working full time and pumping and only pump 6-8 oz. a day so for each bottle, my nanny usually does 2 oz. BM, then 4 oz. water and 2 scoops of formula to make BM last.
I too supplement formula with BM as I do not create enough BM. You can do whatever ratio you want though make sure you LO will take it. My LO is not a bog fan of formula so i use 4 oz bm and 1 oz formula.
Do not use BM in place of water when mixing the formula! My LO has her BM fortified with formula due to a CHD and it is a very precise process so she doesn't get too many calories given to me by a dietician. And you should never put a scoop of formula powder in 2 ozs of BM.