Hi SilvanG,

If you're only creating your Components from the toolbox then you can override MergeConfigure on Component and create the child there.

If someone might be hand-editing your xml files, then you might want to look into overriding the postload event handler on your DocData to fix up any Components which don't have the right children.

If instead you want different toolbox entries having different combinations of children then you can instead set up different ElementGroupPrototypes with different subgraphs by overriding your ToolboxHelper class' CreateToolboxItems method.