Compound objects

Hi,

I'm preparing a control (Avalanche) based on simgroup with three subobjects inside (two markers and one trigger).
When I put my control in editor I get an appropriate structure - a group with three objects inside but all these objects aren't valid.

This control is made in c++ code, markers and triggers are private members of it. in onAdd() method I register all these objects and add them to my control group.

In editor's scripts I build my control using:

function ObjectBuilderGui::buildAvalanche(%this)
{
   %this.className = "Avalanche";
   %this.process();
}

What I missed? How to create such a compound objects?

Regards

Ania