Updating Pond Members
You should always send the complete list of User ids in the
userIdsfield if the field is present in your request. To remove a user from the pond, first make a GET request to /ponds/:id to get the current members, remove any ids you wish to remove from the pond, add any ids of user you wish to add to the pond, and then send the full list of user ids back with a PUT request to this endpoint.
Try It! to start a request and see the response here!