If you sell a product on Bol.com that is available in different sizes, your sizes might turn up separately on Bol.com. If you want your sizes to be grouped together and displayed as one product available in different sizes on Bol.com, you will need to contact Bol.com's content service.
You can send an Excel sheet to firstname.lastname@example.org with the EAN codes of the sizes your want to group in one column and in the second column you indicate which of the EANs should be grouped together on Bol.com (with for example an item group ID).
Bol.com will charge a fee for every EAN in the spreadsheet that they need to group together, as it is a manual process. For more information you can contact the Bol.com content service.