QSortFilterProxyModel

Hello, i have some question`s

Basic structure

A|
--AA|
Item 1
Item 2
Item 3

after set proxyModel(mapping)
A|
--AA|
Item 1, Item 2, Item 3

i want know that QSortFilterProxyModel - mapToSource , mapFromSource can`t reimplement ?

i want TreeView - viewmodel - proxyModel(Filter) - proxyModel(mapping) structure

Is it correct that the mapping proxy model should be an intermediate model?

plz , answer !