My Ds spend his first weeks in intensive care and a lot of the mums there had to top up the feeds with formula. The formula they used in this hospital was nutramigen because it is the one that causes least allergy.
I saw the babies happily drinking their expressed breastmilk. (most were too weak to breastfeed).
Then the nurses decided that one or two ounce or whatever the amount, wasn't enough so they gave them nutramigen.
It stinks and I wouldn't drink it and none of the babies there did. The mums and the nurses had a really hard time getting that stinky stuff into the babies and it staying there
In Germany we have loads of brands of hypoallergenic formula, every big brand (Nestle, Hipp, Milupa etc) had their own hypoallergenic version. That's what we fed our baby. I don't know where you are but is it possible to change to another formula or add something to nutramigen? Maybe you can check with the ped and ask if it's okay to add baby tea or something to it for the taste
Good Luck!!!