In case of WILL, prefer to register, as registered WUILL is not easily set aside on the counts of authenticity.
Any WILL can be contested and in such case the WILL lands up in probate court of pecuniary jurisdiction. This has its own cost and time factors.
It is mandatory to probate the WILL in areas of Bombay, Madras, Calcutta………..
As your mother is alive, she can dispose her property by a valid/registered deed n her life time e.g; WILL, Gift, sale, transfer, release, settlement deed with life rights etc etc , in anyone’s favor…