Can you stay 1 night with family in a disney hotel?

I am thinking about suprising my family when they go on a vacationi to Disney World. I already have tickets and can get my own airfare and transportation from the airport. Will I be able to spend one overnight in their hotel room with them or do I have to book a one night stay in a Disney hotel? This would be a total surprise. I want to suprise their 5 year old for her birthday, and just walk into their character breakfast with her present, then spend the day with them... she would be so suprised!