if your favorite skin has a nondefault skin detail/makeup version, open that in sims 4 studio, and a window will pop up. this has to be a nondefault version of a skin overlay-it can be set as a skin detail, or maybe makeup, whatever. first, i went into sims 4 studio, and went file > open > then i clicked the package file of the skin overlay i wanted.whoever has a better way to do this, i’d totally love to know how! this is just how i jerryrigged it for the time being :) it’s also not a way to fix default skins it’s just a way to get your infant to have the skin you like. This is not by any means a long-term fix or even probably the most convenient way to do this, it’s just what i ended up doing for the moment so that the babies would be cute. For people asking how i figured out how to get things like skin overlays enabled for infants (namely & on my post).