How can I set up Thunderbird mobile to display all emails in a threaded conversation view

Hi, I've been using Thunderbid Mobile from early beta but I've never managed to achieve what the desktop application (and many other applications) do out of the box: I want threaded views of an email conversation to display both sent and received emails (as well as those archived). I expected this to work out-of-the-box, but it has never worked and I've never been able to figure out how to tweak settings to make it work. I thought the unified view might allow what I want, but if I enable my "Inbox" and "Sent" (and Archive) folders to be unified I get a merged view of their content but the threaded view of emails does not work, I sent items separate from replies received to these. I need help how to fix this because it has become severely limiting and it is pushing me to switch to another client if I can't find a solution. Thanks, Szilard