Parece que o atributo [BsonIgnore] fez o trabalho.
public class GroceryList : MongoEntity<ObjectId>
{
public FacebookList Owner { get; set; }
[BsonIgnore]
public bool IsOwner { get; set; }
}
public class GroceryList : MongoEntity<ObjectId>
{
public FacebookList Owner { get; set; }
[BsonIgnore]
public bool IsOwner { get; set; }
}