Is this just an issue during the summer or do your husband and daughter sleep in after 7 during the school year as well?
So hard to address this. My brother is LOUD as well...the whole family my sister in law, brother, nephews they have no concept of "shhhhhh baby is sleeping". It drives me up the wall when they come visit (they stay for a good 10days) things are just way louder. They are just innately loud and they do things differently (babies/kids napping sure ok...they blast the music and talk loudly).
You'll need to either accept that your hours start at 7am and at 7am loud people come. Or, you'll need to address this issue flat out. Not just a 'shhhh baby is sleeping' at the door because that means nothing to them because odds are they don't realize they are loud or that they need to be quieter with a baby is sleeping. You'll need to talk to them in person. Let them know they are loud, that they are waking your daughter, husband and DCchild. Tell them you NEED them to enter quietly. Send the same info home in writing after you talk to them.