too long

I've been using twitter api for a while and I'm still looking for some way to implement a download method for DMs at conversation DM.

My code looks like this in this moment:

$connection->request('GET', $connection->url('1.1/direct_messages'),///events/list'), 
          array('include_entities' => 'true',
            'count' => 100,
            'since_id' => $since_id));

I've both tried old direct_messages and new events/list endpoints, but seems that I'm unable to download conversational messages. For example:

DM between person A and B:
A: Hi
B: Hello

DM between person A, B and C:
A: Hi converstion 2
B: Hello conversation 2
C: I'm new!

I expect to get some list like:
[Hi, Hello, Hi conversation 2, Hello conversation 2, I'm new!]

But I get:
[Hi, Hello]

Is there any way to handle this? I can't find the reason why I can't get messages from the conversation from 3 or more twitter users...

Thanks in advance!

The Twitter API does not support group messaging. This feature is only available through the web site.