Mrs Joseph asks How do you propose that works? Suppose someone changes from x to z … stick to his original mesorah insofar as x minhagim…but suddenly start following the “hashkafos” of y?
Let me answer slowly so you can follow.
Yidden from the Old Country arrived in the early Yishuv of EY.
Many kept their hashkofos but took on minhagei EY.
Example one of numerous, talmidei HaGra of EY have unique minhagim that the talmidei HaGRa of CHUTZ do not have.
That is how it works.
People “evolve” according to their community and hashkofos while keeping certain core mionhagim and mesorah. Yes, sometimes, those are lost and it is hard to identify them with the “original” mesorah (as exampe cited).