Maternity Benefit - 3 month paid leave & Disbursement of this maternity break salary will be done once employee joins back!?

Dear Colleagues, I work with a Pvt. School. of Delhi.
W.r.t. Maternity Benefits - as per the HR Policy here, an empolyee is eligible for this benefit :
1) Only if she has completed 2 year service with the organisation.
2) Only 3 month paid leave is allowed. It can be extended upto 6 months. But beyond 3months, additional leave will remain unpaid.
3) Disbursement of this maternity break salary will be done once employee joins back post break. Payable as additional 1 month salary for 3 months from 3rd month onwards of joining back. ( i.e. 3rd, 4th & 5th month after rejoining ). If employee leave in between then no maternity break salary.
For example : If Miss A goes on break on 1st January, then she has to join back on 1st April ( Post 3 months from starting of break ), her maternity break salary of Jan to March ( break period ) will be paid in June to August ( In 3rd to 5th month from date of joining back - 1 month additional salary each ) .
My question is - it allowed / legal to mandate point no. 3. Plz suggest.

Dear Deepika,
I would request you to go through the Maternity Benefit Act,1961 first and make sure that the Act applies to your school.
If the Act is applicable, all the three norms mentioned above as the parts of the HR Policy of the school are running counter to the corresponding provisions of the Act,1961 and therefore illegal.

W.r.t. Maternity Benefits - as per the HR Policy here, an empolyee is eligible for this benefit :
1) Only if she has completed 2 year service with the organisation.There is no such clause in MB Act,
2) Only 3 month paid leave is allowed. It can be extended upto 6 months. But beyond 3months, additional leave will remain unpaid.It is 6 months, as per MB Amendment 2016, 3 months was earlier i.e. prior to 2016
3) Disbursement of this maternity break salary will be done once employee joins back post break. Payable as additional 1 month salary for 3 months from 3rd month onwards of joining back. ( i.e. 3rd, 4th & 5th month after rejoining ). If employee leave in between then no maternity break salary.Again it is illegal as such no such provision in MB Act

Thank you Mr. Saji & Mr. Umakanthan.M for your revert.