Welcome to planDisney, Stefanie!
It sounds like you've got your work cut out for you with three Mouseketeers. However, I trust you'll have an enchanting time at The World's Most Magical Place. There are so many things for little ones to experience and enjoy. Did you hear that
Enchanted Tales with Belle is coming back to Magic Kingdom Park on February 19? I know your kiddos will love taking part in a tale as old as time.
Stefanie,
the current rules state that strollers larger than 31” (79 cm) in width and 52” (132cm) in length are not permitted. Therefore, your double stroller would most likely not be allowed in the theme parks. If you show up with an oversized stroller then you risk not being allowed to take it with you into the parks. I realize that's not the answer you wanted to hear. However, you do have another couple of options, Stefanie.
Renting a stroller at the Walt Disney World Resort is super simple. You can rent them near the front of all four theme parks once the park opens. You can also rent them at Disney Springs. At this time, you can't reserve a stroller in advance. However, even though availability is limited, there are loads to go around and so I doubt you'll have any trouble.
You can even purchase a Length of Stay Rental for the number of days that you plan on being in the theme parks. This will actually save you money over the daily rate. You'll just need to show your receipt on any subsequent days. You can't take your stroller outside of the theme parks. So you'll have to pick up a new one each day. One of the cool things about renting a stroller is that they have a snazzy Mickey and Minnie design!
Another option for you is to rent a stroller from an outside company. There are several companies that deliver strollers right to your Disney Resorts Collection hotel. For example, ScooterBug is an official Disney Featured Provider and will drop off and pick up strollers at your hotel. You don't even need to be present! You can even pre-order a stroller ahead of time. My family have used this company in the past and had a great experience.
I hope that's helpful, Stefanie! I hope you have a brilliant trip.
Mike