Hey Howdy Hey Sherri and welcome to planDisney!
Your family is in for such a Magical time with the experience to go on
Disney's Keys to the Kingdom Tour in Magic Kingdom. I had the opportunity to go on this tour a few years ago and it was so amazing, I am so excited for your family! The specifics of the timing on when to get into the park and how can leave a lot to the imagination especially first thing in the morning, so let's go through how to do this.
First off, make sure they follow the instructions for the tour in that they do get there early and are in front of City Hall at the designated time. The front entrance will be closed to those for regular park admission but yes, there is a special entrance for those expected to be early for the tour. Most times there will be a Cast Member holding a sign that will say something like "Special Event" on the sign, so I would try to find that Cast Member with the special sign. Your family will also be able to ask any Cast Member and they will be shown where to go and allowed in early to get to the designated meeting place.
If you are planning on meeting up with them in Magic Kingdom after the tour, the
Main Street Bakery is always such a great place to visit. I mean coffee and a Mickey-shaped cinnamon roll, how can that be bad right?
I hope you all have a great time on the tour and a Magical stay here in the Vacation Kingdom o the World! Let us know if you have any further questions.
Have a Magical Day,
Nick