Hi Julie!
When I have gone with my family to the Disney parks, it's been my experience that they checked for our valid FL ID (the adults and older kids). I'm unfamiliar with tickets purchased through ebay, as I myself am wary of purchasing tickets on there.
If you are not a FL resident with valid ID, and provided that the tickets you have are valid, you will have to go to Guest Relations before entering the park and have your tickets "upgraded" to non-resident passes, paying any price difference applicable.
If you'd like to call ahead to hear what you might expect, I've included a link below with some Disney Contact Info, and I would advise that you get in touch with "Tickets" listed on the right side of the page.
Walt Disney World Contact Info
I hope this helps! Feel free to come back to the Moms Panel if you need anymore help!