We had to change plans last minute last year from WDW to DLR. We had tickets to
MNSSHP at WDW but by the time we changed our plans, OBB was long sold out. I called Disney several times and the DLH where we were staying, and no one would give me a definite answer as to the possibility of some same-day tickets being sold to onsite guests. When I checked in, I asked the front desk CM and she confirmed that they had very limited availability, but that I needed to be at the front desk at 0500 on the day of the party to try to purchase them. They had enough for the first 7-8 families (all resorts share the tickets). So don't completely lose hope because my experience with the CMs was that none would commit to "yes" until we actually arrived. I hope you can get some tickets!