I don’t think they would crowd the resorts they’re filling, if this does happen. I think they would keep distancing in mind. Mind you, some resorts can absorb crowds better than others and it may go somewhat unnoticed.
They could probably fill BLT, for example, as the transportation and food location are built to accommodate people from both BLT and Contemporary. Pool would probably be the main concern. BWV could probably be filled, everything at that resort including the pool is meant to handle crowds from the inn side as well. I feel like elevators are the most crowded part of that resort

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I think it’s the dedicated DVC resorts that could be more of an issue, but then again doesn’t DVC operate sold out year round?