You are already paying ₹15 Lakhs alimony and ₹10 Lakhs child settlement.

. A "Full and Final" settlement means zero ongoing monthly maintenance or school fee liabilities.

2)Paying a ₹20k monthly school fee creates an open-ended, lifelong liability.fees tend to increase every year 

3)If mediation stalls, offer that the ₹10 Lakhs is locked, but the monthly interest (approx. ₹5,500-6,000) goes directly to the school for fees.

4) you can insert a clause in settlement agreement 

Any change of school, major medical treatment, or extra-curricular expense exceeding ₹5,000 per month requires prior written consent from the father. Unilateral decisions will be funded entirely by the enrolling parent."

-  You can enter into an agreement /MOU with her in the said mediation settlement after giving full details of payment 

- Further, you can mention therein that after this payment she will have no right to claim any maintenance or any amount for herself and not for the child , as she is getting full and final settlement amount from you. 

- If you are going for divorce then better pay the said amount before the Court after agreed before the mediation cell . 

You can state clearly on record during mediation: "The father wants the best education, but the mother enrolled the child in a ₹20,000/month school unilaterally without consulting the father. The father’s financial capacity does not allow a ₹2.4 Lakh per annum school fee on top of a ₹15 Lakh alimony and ₹10 Lakh lump sum."

You are asking for 3 days of custody (weekends). If you are keeping the child for 3 out of 7 days, you are already bearing 40% of the child's boarding, lodging, food, and entertainment expenses during the week. Use this to argue down any further monthly maintenance demands.

Whatever you agree to (whether it is the FD or a modified monthly amount), the mediation settlement must explicitly state: "This is a full and final settlement. The Second Party (Wife) waives all rights to claim any further interim, permanent, or future maintenance for herself or the child under any law (Sec 125 CrPC, HMA, etc.)."

You can say this to the mediator "I want to secure my son's future, which is why I am offering ₹10 Lakhs despite being heavily stretched. However, because I am giving this large amount upfront, I cannot pay an additional ₹20,000 a month for a school I did not choose. I propose that the interest from a portion of this ₹10 Lakhs go to her monthly for school expenses, and as a capable mother, she must cover the rest. This must be the final settlement."

They do not want to go to court any more than you do; they are simply testing your boundaries to see how much more they can extract before signing.

You can decide whatever you feel in mediation it’s not compulsory or mandatory. Even whatever decided in mediation is not applicant in court if it fails. Therefore you can decide your terms if not happy contest it on merits in court 

Hello, 

1. If the wife doesn't agree with the proposal of 10 lacs FD, you may suggest paying for the school fee entirely and insist that the choice of school is done by consensus.
2. As it is your proposal is reasonable and if it is not agreed, you can choose not to stretch and decline.
3. The more you negotiate the more difficult it will become. Your lawyer's advice is reasonable.