I really need to figure out how to be more assertive with my baby's care. My in laws just jump in…

I really need to figure out how to be more assertive with my baby's care. My in laws just jump in and have this bad habit of overstimulation him when I'm trying to get him to sleep at night. Seriously. All I had left was a diaper change. He was already out. I asked my husband to change him and he drags his mom and sister in and they wake him up and fuss over him. It's 1030 at night. He's a breast fed baby in a growth spurt. This mama is exhausted and overwhelmed. It's one thing to fuss over him during the day in another room but it's a whole different thing when it's late and in MY room.