I can verify that. You can use a children's AP for rooms (up to three of them)
You would not be doing anything wrong or shady..that is how Disney allows the system to work.
Disney says:
Passholder Benefits Summary
Discover the many benefits of being a Walt Disney World® Passholder. With several Passes to choose from, there's one that is just right for you.
Benefits include:
Special Passholder events throughout the year, like attraction previews.
Merchandise discounts at select Downtown Disney® Area locations, including World of Disney® Orlando.
Food and Beverage discounts at select Epcot®, Disney's Animal Kingdom® Theme Park, Downtown Disney® Area and Walt Disney World® Resort locations, including Le Cellier Steakhouse, Olivia's Café and Wolfgang Puck® Express.
Periodic Walt Disney World® Resort room discounts
Plus, you will receive discounts on select Theme Park tours, golf, miniature golf, spa treatments and more!
Become a Walt Disney World® Passholder and see how an Annual Pass is like your own magic wand!