For the most part, toddlers interrupt adult conversations because it works. What usually happens is, mom or dad will reprimand the child for interrupting — then exasperatedly answer the question the child was asking so they can continue their adult conversation. So, if you want your child to stop butting into your conversation, don’t answer their questions when they do.
Instead, respond the way you would to another adult by telling them you’ll be with them as soon as you can. In the case that she may be asking you something urgent, teach her the right way to interrupt — by saying excuse me, then letting you decide if it’s something that can wait.