Adding taxonomy term list to another taxonomy term's overview
In this case you need to a create view that displays block on top of the collection page.
The view should display taxonomy terms in the "collections" vocabulary filtered by a contextual filter (taxonomy term id) so that only the desired taxonomy term is display.
Next you should add a relationship using the field reference you're using on that term.
Finally you can use the relationship to display fields or taxonomy terms to the display.  

I tried to explain it briefly, let me know if you need further explanation.