Hey there, hi there Maura! Welcome!
As you obviously know, all
Walt Disney World theme parks now require not only a
valid theme park admission, but you also have to have a
theme park reservation to go into any of the parks. That means that yes, your husband would need a reservation to go into
Magic Kingdom park with you and your daughter.
Don't despair, though, Maura. Maybe we can figure this out. First, do you have the
park hopper option on your theme park tickets? If you buy your husband a ticket with the park hopper option, as long as he scans into another theme park earlier in the day, at 2 PM, he can hop over to another park - including Magic Kingdom. If there's another park available for your Magic Kingdom day, this might be a workaround for you.
Another option is to just keep trying. I know it sounds like a lost cause, but even last week - one of the busiest because of spring break and Easter - I was able to score a last-minute theme park reservation. I just kept checking periodically throughout the day, and the night before, we were able to get a reservation for two of the parks. If you just keep checking the availability calendar whenever you think of it, you might find one.
I don't know how many days you're staying, but is it possible to swap your Magic Kingdom day with another day? If there are available reservations at Magic Kingdom on another day of your trip, maybe you can switch your Magic Kingdom day to that day.
I hope it all works, Maura!
Anna