If You Have Two Kids, is it Okay to Bring the Sibling to the Party?
In general, it’s expected for a parent or caregiver to stick around during parties for infants and toddlers, says Post, and in our experience, even through preschool. After that, she suggests asking the host what they prefer.
If you have siblings to deal with, it’s inappropriate to ask if you can bring them along. Try to make other arrangements, or call the hosts and ask if they would be okay with you dropping your child off instead of staying. That also allows them to say, “Why don’t you bring the whole family?” Even if you’d only be bringing a newborn in a baby sling, Post says it’s still proper to call the host ahead of time to give her a heads up.