Conducting The union election is the total responsibility of the Labour department. If you have more than one union in the organization then for getting the clarification of the majority the labour department will organize the election and cofirm in writing to the organization about the majority union after conducting the election in a secret ballot mode and the elected union will be in force for 2 yrs. The management should negotiate with the elected union and enter the agreements with them only.
If a single union is there then there is no necessity for any election and it continues till some body challenges their majority.
The office bearers election and selection is the internal process of the union and no way the mangement is connected with that. Some time the unions will contest on the panel and some times only banner in general they will go on Union president vs union president and after winning the fray they will declare the body.
Regards - kamesh