1. Our POA mentioned there is a problem in the sale of land so they need to appeal a case in the high court, for that they need "life certificate" of my grandpa and his two daughters. Is the life certificate is really required for appeal a case in high court?
Yes life certificate of all principles of the power deed are necessary to establish that the POA deed is valid as on the current date because upon the death of a principal the deed will be infructuous and invalid.
2. we asked our POA to provide any approval document that he will not do any sale or any transaction without our knowledge. - but he refused to do that. - let us know is there any other way that we can safe our property from the illegal transaction by our POA.
If all the principals are alive then they can jointly issue a notice to the agent stating that the POA deed is revoked and they cancel the same hence his such agency is terminated due to cancellation of the said deed. This way you can protect the property from being alienated without your knowledge.
3. If there any way, our POA can sold our land to other person and completed the registration also without our knowledge and not paying any amount to us? If this happens please let us know how we need to proceed.
The POA agent cannot take the payment of the sold land, i.e., he cannot retain the consideration amount, he has to hand it over to the principal, if he is not doing so, you may immediately cancel the deed and file a suto for recovery of money from him.