@Simmer2029 I would love to be able to do this as well. Though one trick you can try is making & deleting the connecting relative - for example, in CAS, if you’ve made an elder and a kid, and you want the kid to be their grandchild, make another random adult Sim. You needn’t bother styling them. Set them as the kid’s parent, and as the elder’s child. If you check the relationship between elder & kid, you’ll see they’re now properly a grandparent. Delete the parent.