Insert a new session (2a, so to speak) which checks that particular flag table. If it contains a T record, make it create one dummy output record; if it does not contain T, do NOT create a dummy record.
Now in the workflow set up workflow link conditions to the new session and to the original third session; the link condition to the new session should look something like this:
$s_m_2a.Status = SUCCEEDED AND $s_m_2a.TgtSuccessRows = 1
Whereas the link condition to the original third session looks something like this:
$s_m_2a.Status = SUCCEEDED AND $s_m_2a.TgtSuccessRows = 0