Siblings bathing together

We’re going to be moving in my mom and step for a short period of time until we purchase our home (moving out of state). They said they don’t mind and we can stay however long we want. I don’t want to intrude on their routine more than I have to so by saving some time I was thinking of having my 5 month old boy and 5 year old girl bathe together. Is this weird? I totally don’t mind at all bathing them separate. It was just a thought.