Minors claim on Fathers property

I have purchased a flat in Bangalore five years back when the owner of the flat has two minor children. previous owner has passed away and now the elder child is major(22 now) and younger one (17years) send a advocate notice that they require their share (ie2/3 of the property value). There are below clause in sale deed telling 1) Property is free from all encumbrance, claims, charges and demands and that there are no litigation in respect of the title of schedule ‘C’ property and the VENDORS have not done anything whereby the schedule C may be subjected to any court attachment or lien of any persons/bank, whatsoever and that there are no minor’s claim or claims of any other person/s whatsoever. 2) Furthermore, Vendors shall all times, hereafter indemnify and keep indemnified the purchasers against any loss, damages,costs charges if any suffered by reason of any defect in the title of vendor or any claims made by any person/s claiming in trust for the vendors. Could you advise what i should do to reply for this and what will be future for this case. Regards Rakesh