How do I subscribe action cable receiver to a new stream without resetting the entire channel subscription?

I have an inbuilt chat service on my application. A signed in user will select another user to start a conversation with them. How can I send stream for this new conversation to the 2 users without making them refetch subscriptions?
The only way it works as of now is re-subscribing to the conversations channel (refreshing the page emulates this).

def subscribed 
 conversations = current_user.conversations
 conversations.each do |conversation|
  stream_from "conversations:#{conversation.id}"
 end
end

This is the subscribed function I have. Whenever a user creates a new conversation current_user.conversations will change but to stream from the new conversation the subscription needs to be reset. Any ideas on a workaround ?

Hi,
I know it has been a year since this question was asked but I'd like to propose a solution (and get feedback eventually).

IMPORTANT
Note that your channel subscriptions are public, so with the following example somebody could do in the browser console:

App.thins.perform('add_new_thing_stream', { channel: 'whatever'})

and the user will be streaming fron 'whatever'
the ThingChannel#add_new_thing_stream here need more work to prevent users from streaming from whatever they want.
------

Here is the idea of how to do it (in a rails 5.2 app):

# thing_channel.rb
class ThingChannel < ApplicationCable::Channel
  def subscribe
    ...
    stream_from "new_things_for:#{current_user.id}"
    ...
  end
    ...
  def add_new_thing_stream(data)
    stream_from data['channel']
  end
end

# when broadcasting
ActionCable.server.broadcast( "new_chat_rooms_for:#{user.id}", datas....)

# thing.js
App.chatRoom = App.cable.subscriptions.create("ThingChannel", {
...
  received: function(data) {
    ...
    this.perform("add_new_thing_stream", { channel: data.channel } );
    ...
  }
}
...

It's far from perfect but it do the job.

So if anybody has another solution or an opinion about this one, I'd be glad to see it :)