I think you must be talking about their "Good Neighbor" parks which are available for a higher fee than the regular membership parks. These parks are still a part of the system I believe.
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Encore" parks are, as far as I know, a group of parks that are run by a company other than Good Sam and are mostly "over 50" type parks with many park models and activities for snow birds. I don't think they have ever been a part of the Coast to Coast network of parks but could be wrong on that. Perhaps a few individual parks were.
Edit: It looks like the Encore parks are a part of the Thousand Trails membership camping network and not the Coast to Coast network.
Barney