some explanation on unbound hierarchical mode please

Hi,

 I've gone through this page and have a few questions:

 http://www.telerik.com/help/winforms/gridview-populating-with-data-unbound-mode.html

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Reason for using Unbound Mode: I'm building a Multi-threaded application, this application has several slow processes in the background and each of them returns a value. I use these values to fill cells in a gridview one by one without blocking the rest of the user interface. I've got this working quite well and happy with the result. I couldn't have done this with binding (this would have resulted in constantly fully reloading the gridview, now I just modify each cell when needed). This is the reason, why I'm using unbound mode.

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Now, for my next modification - I need a hierarchy in the gridview and I'm having trouble getting this to work:

I need something like the following:

Now, when following the steps for "hierarchical grid in unbound mode" I'm getting way too many child rows. I believe the reason for this is because I'm using a template like so:

Then I loop through the amount of childrows that need to be created like so:

This results in having way too many childrows. I've just taken two random columnnames as the relationship => I'm assuming this is probably the reason why things aren't working.
The thing is, in my case there is no real relationship between child and parent. The parent is just the average values of all children. Does this mean I need to create an extra column just for the sake of the relationship ?

Also, when using unbound mode (in a non-hierarchical situation) I first create the rows, and then fill them. If in hierarchical mode, I'm getting the impression that I can't create the childrows without filling them (not sure)?

All I really want to do, is create child rows an fill the cells one by one, whenever I can....

Thanks in advance for the help and example !