Dear Baskkaran,
If your management has accorded the status of recognized union to any union based on its majority membership, any long term settlement concerning common issues as a result of bilateral negotiations can be signed by the recognized union.But there is no bar to allow the unrecognized unions also to sign, if they accept the settlement.Such a practice would be a prudent one in the situation of multiplicity of unions and avoid disputes in future on the settled issues. In case of a tripartite settlement before a conciliation officer, he would invite all the unions for conciliation and effect a settlement based on the acceptance of majority.