A new arrival gives people plenty to gossip about.
You'd rather not get involved in this particular argument, but you may not have a choice. If you are forced to give an opinion, do so with careful tact. People may try to make you choose sides, but you don't have to do that.
A lack of role clarity, where you don't know what is expected of you, is a leading cause of job dissatisfaction and stress. Seek clarity as soon as possible.