My first 2 babies were formula fed and I had them weaned off the bottle by 13 months (my third is breastfed , but his daytime feeds are cut out now just morning and evening), so this isn't something I would personally encourage....but at the same time, if this is the parent's dietary request, and his dr's, then I would just continue and stop worrying about it. The recommendation is for babies to be breastfed for their first two years of life now, so I don't see the harm in the continuation of formula either. If the concern is based mostly around the suspicion of a milk protein intolerance, then I would leave that to the parent and doctor. You've already expressed your concerns to deaf ears, so I would just carry on.