A few things you need to know in general;
- the XPath query or datasource micro/nanoflow set on a reference selector will be executed when the page opens, not when stepping into it
- When refreshing the context object of the enclosing dataview will refresh the reference selectors and re-execute the XPath query or Micro/nanoflow
- Connecting 2 different entities to the same reference selector is not possible in any case
Knowing this you can
- on change/select of the first value → execute nanoflow which refreshes the context object
- Specify an XPath or Micro/nanoflow which will define the selectable objects
- Add two different reference selectors and set visibility based on the selection in preceding reference selector and thus show only one, depending on the selection.