Don't understand what is meant "calls its render function".
What is product browser?
Let say on the left you have list of products, on the right - selected product rendered specification. Right? If something like that:
1) list of products - one control which renders Observe.List (list of products)
2) product specification - second control which renders currently selected product. You just should should for example initiate new control instance (or update existing passing new selected product) when other product in list control is selected.
If you product control deals with editing of selected product you really should not have controls for all items initiated, you should have only one at a time depending let say on which product is selected.