Can a school stop giving TC if mother stops working in the same school and resigns?

Dear Sir I was working with Global Indian International School in Peerzadiguda, Hyderabad from 2010 to 2018 and had resigned on March 24th by giving 1 month notice ie on 24th Feb. I have shifted to other place. I have completed academic year, PTM and then informed them to give my NOC and relieve me on March 24th 2018. In 1 month notice period the management did not tell me anything in spite of reminding my due date, but now after I joined in another school DPS Nacharam, Hyderabad, they are demanding to pay 3 months salary. They did not pay my March salary as well as my arrears of 2017-18. They with held my B.ed Convocation certificate and 8 years experience certificate. Now they are calling me every day and also sending mails to pay 3 months salary and complete the formalities. I feel its unfair for the employee who served 8 years in the institution continuously. When I approached they said they can waive off as I worked for many years. But when I informed that I have joined DPS school, they started demanding 3 months salary My daughter completed her 10 th std from same school. Now they are troubling her by not giving her TC, Bonafide and grade X certificate. They have given child benefit policy. Can you please tell me what can the school do if I don't pay them. HR is saying that according to the appointment letter we should resign before DEC. Kindly suggest me what to do. I can't afford to pay to the management. They are not considering 1 month notice period. Please suggest. My child is scared as her college is demanding to submit grade X TC immediately otherwise admission would be cancelled. How can my job be linked with my daughter's education? I will be waiting for your reply.