As an introverted child, your daughter gets drained of energy when in public. So let your child have her private time before guests come in so she can spend a little time with them before she retires to her room. Also prepping her in advance will help. Do not force your child to interact if she doesn’t want to. Be positive and get her to understand how you feel if she locks herself off. Ask her to just say hello and sit around for some time before she goes back to his room.