In Brickstore, there is an option “Export List XML to clipboard”. Use it after loading
the parts-list file and press OK. Then the Bricklink site opens on the "Wanted list
Mass Upload page". Paste the wanted list to the entry field (Ctrl + V) and press
"verify items". Scroll down and press "Upload file" and then "view your updated wanted
If you go to the (next) tab "By shop" you can see which shop have how many of the
parts you need.