Baby onesie disappears with age up?

[MEGABYTESMA]

My sim knitted a baby onesie and dressed the baby in it. When the baby aged up, the onesie seems to be gone now. It's not in the mom's or baby's inventory. I really love the baby onesies but don't want to knit a new one for each baby (doing the 100 baby challenge). Is this supposed to happen or is this an error? Thanks!

I don't have any CC, mods, or cheats. 

[jpkarlsen]

@MEGABYTESMA 

As babies do not have a clothes category in CAS this was the only way possible to give them a onesie.

[MEGABYTESMA]

I'm very happy with the onesies and how to dress the babies. I just wish you got the onesie back when the baby ages up while wearing it.

[jonesc1204]

This happens to me too. The onesies come from the nifty knitting pack. You have to take the onesie off before aging up.

[abgirlee]

Is there not a way to code it so the baby onesies go back into the mother's inventory? This is really annoying when doing 100 baby challenge, which is the only way I can play this boring game.