Oh my god, I don't know what happened!
It was Luke's birthday from a baby to a toddler, so automatically my pregnant mother went to "Help With Birthday", went upstairs to his cot [the one tile one that I downloaded earlier, in case that has anything to do with it...], went to pick him up and *poof* he was gone.
He wasn't in the cot and he disappeared from the family on the left hand side, yet I checked the family tree and he's still there, attached, saying he's alive, and he's still classed as a son and friend in the mother's relations, so what's going on?!
How do I get my baby back?! All help appreciated, so thank you so much in advance.
Edit:// I resolved the issue by using the Teleporter from Simlogical to summon Luke, then using the boolprops to make him selectable [adding him to the family], setting it to his birthday, making him grow up and voila! He's a toddler, just like he was supposed to be
