replaceLastName with nested navigation

[BarashkovaElena]

I cannot figure out how to make replaceLastName work with nested navigation, need some help on that.
There is a root navigator and a a nested navigator. I want to open a page inside a tab in the nested navigator and then replace it with another page. I perform the following steps:

1. Open nested navigation page. Stack tree initially looks like this:

Key [-1] (Root)
Key [2] (bottom_bar_page)

Key [20] (bottom_bar_page)
Key [3] (home)

2. Open nested page over the home tab. Stack tree becomes this:

Key [-1] (Root)
Key [2] (bottom_bar_page)

Key [20] (bottom_bar_page)
Key [3] (home)
Key [4] (internal)

3. Call QR.navigatorOf(bottomBarPageName).replaceLastName(dtoPageName);
   Stack tree becomes this:

Key [-1] (Root)
Key [2] (bottom_bar_page)

Key [20] (bottom_bar_page)
Key [4] (internal)
Key [3] (home)
Key [6] (dto)

This is not correct, because "internal" page should not be in the stack. It should contain only "home" and "dto".
I need to get this stack:

Key [-1] (Root)
Key [2] (bottom_bar_page)

Key [20] (bottom_bar_page)
Key [3] (home)
Key [6] (dto)

If I call replaceLastNamed on the root navigation, then the app crashes:

#2      NavigatorState.initState (package:flutter/src/widgets/navigator.dart:3577:14)
#3      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:5618:55)
#4      ComponentElement.mount (package:flutter/src/widgets/framework.dart:5463:5)
...     Normal element mounting (48 frames)
#52     Element.inflateWidget (package:flutter/src/widgets/framework.dart:4340:16)
#53     MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6904:36)
#54     MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6916:32)
...     Normal element mounting (380 frames)
#434    Element.inflateWidget (package:flutter/src/widgets/framework.dart:4340:16)
#435    MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6904:36)
#436    Element.updateChild (package:flutter/src/widgets/framework.dart:3849:18)
#437    Element.updateChildren (package:flutter/src/widgets/framework.dart:4036:32)
#438    MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6929:17)
#439    Element.updateChild (package:flutter/src/widgets/framework.dart:3827:15)
#440    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5512:16)
#441    StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5650:11)

How to get the desired stack tree?