Hi BR001,
The 3 fields that have code in layout:ready event should have height as that of their child subforms. So.
ImageField1,Cell1 (at bottom in hierarchy) in SF1_Container should have height determined by height of SF2_Container
Cell2 in SF2_Container.SF2 should have height determined by height of SF3_Container
ex. If I add 3 instances of SF3 (say height 25pt) then Cell2 in SF2_Container.SF2 and also ImageField1,Cell1 in SF1_Container should be of height 25*3= 75pts
Similarly, If I add 4 instances of SF2 (say height 25pt) then ImageField1,Cell1 in SF1_Container should be of height 25*4= 100pts
The actual code is as given below for Cell2
form1.Subform1.Table1.Row1.Subform1.SF2_Container.SF2.Cell2::ready:layout - (JavaScript, client)
var heightField = xfa.layout.h(this.parent.SF3_Container, "pt");
this.h = heightField + "pt";
See below image.

Hope this clears.
Regards
Arvind