Denying visitors

Christen

Hi all so this is my first pregnancy and right now at odds with my SO’s sister due to a situation we’re dealing with, there were claims that I had slept with someone and that the baby is not my SO’s when I know for a fact it is and that these claims are lies. She was supposed to be the godmother to my son but as of now is no longer allowed due to her believing the lies and accusing me. Yet my fiancé does believe me and he told his sister to back off. For those who are moms already when I register at the hospital for labor is there a way to where I can deny her to visit me and my son? How do I go about that? TIA!