100 baby challenge: What if sims age up w/o any infant traits?

A couple of the first sims in my game did not age up with any of the infant traits, and I don't know what I'm supposed to do with them.

I was thinking that my matriarch would still have to raise them to adulthood and would not be allowed to have another child using their donor parents, but they would not be a challenge fail and could still help around the house and with caring for other children. I'd set them as a household member so they wouldn't show up in genealogy, and alter romantic/woohoo preferences so that they wouldn't compete with the matriarch for donors or accidentally try and romance the matriarch. Alternatively, I'd have to age them down in CAS and start over until they got the happy or top notch traits, which I think would also be fair since babies are hard to deal with.

However, I'm worried that I might not be able to see some infant traits, or that the traits might be buggy and not show up. There might be a protocol for this, but I haven't found anything online. 

Is there anything you guys do when this happens?