Dear Milee,
You have given some information about hiring trainees in your organisation. Nevertheless, what is your query?
The only thing that I find anomalous is usage of the word "stipend". Stipend is paid under the provisions of Apprentice Act 1961. The minimum amount is decided and revised every year by the Govt. However, employers have liberty to pay more than what is stipulated. Stipend is paid to the apprentices. They are not employees, either regular or contractual. Provisions of ESI Act are applicable for apprentices.
On the other hand, salary is paid to the employees. Employee could be regular, temporary, fixed term or contractual. Rules of payment of monthly salary are governed by Payment of Wages Act, 1936, Shops or Establishment Act or Factories Act etc.
In your case you are not hiring apprentices under the provisions of Apprentice Act hence usage of the "stipend" is improper. What trainees will get is salary.
Thanks,
Dinesh Divekar