You want one Union. The scope isnt broader than in other industries, where from the line worker to the engineer people are also under the same Union contract. The more people you have the more power for negotiations you have.
That's interesting. In which country is that? Here in Germany most union contracts cover an entire industry and all workers in unionized companies there. So an IT employee at a car manufacturer is subject to the same contract as themechanical engineer, the trade master supervisor on the shop floor and the line worker.
It is not in the interest of the employees to be divided as they have the same employer to negotiate with.