When we supplemented my DD (I had absolutely NO stash built up when I went back to work for a number of reasons), I'd instruct the DCP to do different amounts per feed rotating breastmilk & formula until I was able to build up a stash again.
I nursed DD in the a.m. then had the DCP do formula-breastmilk-formula as the day progressed. Obviously you won't have this luxury on a business trip, but you might want to try keeping any stashed breastmilk for feeds at home while you're away & giving formula only at daycare or whatever.
You might want to try a rotation starting now to gauge any possible reactions before you go away. My DD had TERRIBLE gas from all formula, so I had to get the DCP to add a dose of Mylicon to her formula bottles to make sure she didn't get cranky later.
FWIW, my sister tried a ton of formulas for my nephew & he did the best on ready-to-feed Similac, though it's pretty pricey.
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Liz
DD (3/2010)
"Make mistakes! Get messy!" - Miss Frizzle