For a desktop application, I'm trying to design form pages for business objects that can have a dynamic amount of child objects (at least 1).
A business object has a "general" form (that covers all child objects) and one form per child object. A requirement is to have only one view per business object, everything below should be structured within this view (e.g. with tabs)
Now, to save height, I'd like to use one tab pane for having both the "general" form and the child object forms. But since the child tabs are actually sub-items of the general tab, it might be ambiguous to have them in the same tab pane. Sub-tabs would make sense, but I dont want to lose the vertical space. Also, there is often just a single sub-item.
I can think of different solutions: From just treating all elements the same (1), to giving a hint by adding a gap (2) or grouping the elements (3), (4). (4) and (5) claim more vertical space, which I'd like to avoid.
Microsoft's Ribbon does segmenting elegantly, but again, it needs some additional vertical space to display the group label (Ribbons use the titlebar for that)
Can there be issues with this kind of structure? Some feedback or maybe counter proposals would be helpful.