I've had townie-enabled toddler clothing for ages, and it really doesn't take long to do. I am wondering if (if) I could somehow make the baby clothes applicable for different categories. I've got some stand-alone diapers which look too cold for everyday use, but would look nice in an 'underwear' category (likewise some snowsuits which could be shifted to outwerwear).

Yeah, sorry, should have made it clearer/indicated more. On the sidebar there's four babies, and all but one is wearing non-default clothing (baby #3 is in default clothing). This was taken just as the birth started, so no opportunity to go in and change clothes.

Edit: Okay, okay, I am trying not to get all hyper but placing baby clothing in different categories does work. You do need something to manually change a baby's clothing (like the Sim Blender) and anything other than everyday will be completely randomised, but...you can have a baby who has an everyday, underwear, and outerwear outfits (and all non-default).