The Sefer Ashrei Haish quotes Rav Elyashuv
zt"l who says that one who has the Minhag of not eating Gebrokts may change his Minhag
to eating Gebrokts.
It is preferable to make Hatoros Nedarim but not necessary. One
may rely on the Hataras Nedarim made on Erev Rosh Hashana.
Reb Elyashuv holds the
original Chumra of Gebrokts started when Matzohs were thick.
Today there is no chance of
having unbaked flour in our thin Matzos.
For Kitniyos one may not
change , Hataras Nedarim won't help.
Even an Ashkenazia who marries a Sephardi
(follows husbands Minhagim) has to keep her original Chumra and should not eat Kitniyos.
The Chumra of Kitniyos is
different than all other Chumros. Kitniyos was a Kabala Gemura till the end of all
generations. (Ashrei Ha'ish 3)
