03 June 2013
Nothing shall change if the will is registered or not.
The main thing in the given case is that the property was ancestral in the hands of your grandfather so he could not have executed a will. The will is invalid on that ground but if the same has not been challenged by other legal heirs of your grandfather then their right to challenge get exhausted due to lapse of time.
04 June 2013
In other words, Will is valid for bequeathing self-acquired property. Here it is ancestral property and all legal heirs have their rights. If they contest the will is subject to satisfaction of their rights.