EWN understands it could decide today to only discuss its problems with Numsa, at another special meeting.
Zwelinzima Vavi was quoted as saying the meeting is Cosatu’s most important gathering in 30 years.
The contract was signed with foreign-owned firms to build more than 1,000 locomotives.
Jacqueline Phooko is reportedly seeking the costs from Vavi, Cosatu and Numsa.
The lockout includes a handful of companies that refuse to accept a wage deal signed by Numsa and Seifsa.
Cosatu's Zingiswa Losi says its not forming Mawusa and it can’t comment on its existence.