Yes, you can make shuttle reservations from the Radisson ahead of time. You will need to call the hotel directly, not their national reservation number. You do not need to be on a "cruise package" which costs more.
A hint....the early shuttles tend to fill quickly. (I'm politely trying to say that you might not be able to get a decent time even now for a family.) You might decide to drive the family and the luggage over to the port about 10:30 with all your luggage. You check the luggage with the porter, and DW can get in the check in line. You return to the Radisson with only your cruise documents and photo ID (you'll need these to get back into the port). THen, you park and hop the next shuttle back to meet the family. You can almost always get on a shuttle as a single person with no luggage. This is not a big deal if it is only the 2 of you, but with a large family, can make a huge difference in your shuttle time. Just be sure that you KEEP your cruise ticket (documents) and your photo ID....or you will have a hard time getting back in!
Yes, you must meet DW in the line to check in (all adults must present themselves for check in), however, this is not a biggie. If she gets to the front of the line, she can just allow the next person to go...until you get there. Now, in reality, there are about a zillion check in lines, but it's not hard to spot someone.
See you all soon.....it's still icy here...maybe it will warm up before I need to move the car.