The UNICEF FF leaflet says:
Individual bowel habits vary, but as a general rule, bottlefed babies will pass stools that are more solid, but less
frequent, than those of breastfed babies.
You should contact your midwife or health visitor if the number of stools per day changes or your baby shows any signs of discomfort or straining while passing stool.
What if my baby seems constipated?
This may be resolved with closer attention to the way in which the feed is made up, since reconstitution errors (i.e. using more powder than is needed for the volume of water) are not uncommon (Renfrew et al 2003). If this doesn?t resolve the problem, the parents could try changing the brand of first milk that they use. Stool hardness is significantly related to the concentration of calcium soaps of unsaturated fatty acids in the stool, which is in turn related to
the specific composition of the milk (see introduction [Bongers 2007, Alarcon 2002, Forsyth 1999, Lloyd 1999]).
There is no physiological or research basis for offering extra water to an already well-hydrated baby in order to produce softer or more frequent stools (Young 1998).
I think you should consider trying a different first milk. No need to go for a comfort milk before trying other first milks IMP.