How old is your daughter?
We did an in-office dairy challenge. They gave DS 1 oz of milk every 15 minutes until he had had a toddler-sized serving. Four ounces total, I think? And I think they started with a smaller amount than 1 oz for the first "dose" - like they just made sure that it coated his tongue.
We were watching for anaphlatic reactions, and they kept us 2 hours after the challenge was over , for observation. BUT, they (allergy doctor) don't care about delayed reactions, and I think that's where DH and I disagreed. (I thought he had a delayed rxn of sleep disturbance, itchy eczema; DH thought he was fine.)
And you're probably interested in more intolerance, delayed reactions. And if you're re-introducing dairy (after a much longer time away from it, I think), does require starting with yogurt - or probiotics first - so that the system of enzymes and bacteria can re-develop in the gut to digest the milk.
I'm sorry, I'm not giving advice. I'm rambling. I would think you would want to know, "yes, this is the milk" and therefore start with a definite dose of the milk.
DS, 10/07. Allergies: peanut, egg, wheat. We've added dairy back in. And taken it back out again. It causes sandpaper skin with itchy patches and thrashing during sleep. Due w/ #2 late April, 2012.