Problem is that a Will can be registered anywhere in the country, notwithstanding the location of the property mentioned therein. Therefore, you need to hazard a guess and try to get the Will searched in possible locations wherever Father/Mother could have registered the will, if at all it is registered. To start with, a Search may be initiated at the Sub Registrar's Office under whose jurisdiction the property or properties fall. For this purpose SRO can be approached and an application can be filed duly paying the fee.
Even if the search does not turn up any Registered Will, you cannot rule out an unregistered Will which is very much valid if it is the last Will.
One more point is that if there is an unregistered Will subsequent to Registered Will, such last Will shall prevail on all other previous Wills, either Registered or unregistered.
Therefore, it is better and advisable that all Legal Heirs sit together in a meeting in the presence of family Elders and ensure that Will/s if any are all disclosed and act upon the Last Will of the Parent/s.