From the explanation you have given to me through a private message sent to me I understand that you have a factory within the compound of which there is a vacant building and that you want to let out to somebody else to do some business. Now in this scenario, the primary advise that I have is that you cannot let out a portion of the premises which is under a factory owned by you. In another words, somebody else cannot run a business within your factory premises, even if it is a vacant land or building. This is because the entire compound will come under the purview of Factory licence already given to you. As such you cannot let a portion of it to somebody else and allow them to run a separate or different business. If they run it, you will be the occupier of that operation and you will have to cover their employees under your ESI/PF codes. Anything that happens to any of the workers in that factory will be your own responsibility.
If construct a compound wall so that the building will be separated, you can solve the problem. But for that you have to amend the factory lay out, drawing etc given to the Inspector of Factories and Boilers. Do that.