Smarter resize of some Gtk ScrolledWindows and Viewports inside a Window

Question

Basically this is my layout:

Window
-> MainVBox
--> ScrolledWindow (1)
---> Viewport (1)
----> VBox (1)
--> ScrolledWindow (2)
---> Viewport (2)
----> VBox (2)

Where the two ScrolledWindows have the "vertical expand" property setted to be True, the other properties are unchanged.

I'd like to have a smarter resize of these widgets:

• If the window get resized and VBox (1) is taller than VBox (2) then ScrolledWindow (1) should be taller than ScrolledWindow (2). Instead in my program they occupy the same height even if VBox (2) is empty and VBox(1) requires a lot of height.
• ScrolledWindow (1) and (2) should occupy as much space as possible, if available, if respectively VBox (1) and (2) need more height than the one provided.
• ScrolledWindow (1) and (2) should not occupy more space than than the one requested by their child VBoxes, unless the window it's taller. Actually in my program they need around 115px even if they are empty.

There's a way to achieve a similar result?

Thanks.