adding sub-features in Bentley Geospatial Administrator SS2

Hi,

I try to define in Bentley Geospatial Administrator feature for 3D buildings which are devided into walls and roof.

I have already defined primary-feature 'building' as a polygon collection with several properties and I wonder how to define sub-features.

I want walls and roof (two sub-features) to be polygons with different symbology which have properties definied in primary-feature. The placement method would be promote. So I could choose in Bentley Map some existing polygons and promote them to walls sub-feature and then choose polygons for roof sub-feature. So these chosen polygons represent one building with, for example, white walls and red roof.

I added sub-features (polygon) for walls and roof in primary-feature 'building' (polygon collection), changed their symbology (PBS) and defined their 'max occurs' as unbounded and 'delete to parent' as lock. Then I tried to update placement method (with promote) but there was no placement method added for sub-feature...I have only placement for primary-feature in method and operations node...

So maybe someone has already defined similar features and could help me? Tell me what I'm doing wrong and how should I define such features?

Maybe is there any tutorial for defining sub-features?

Regards,

Ula