Multiple languages issue with load of 0CUSTOMER_ATTR sort key

We're in the process of preparing to go live with more countries next year - with different languages. We're having issues in our testing of the load of 0CUSTOMER_ATTR, the sort key for example - because of characters in other languages.

For example in the sort key field: BEGOÑA. The Ñ character is considered invalid by BW.

Of course we can get around this by adding this character to RSKC, but in this case it seems we'd be adding entire language alphabets to RSKC!

Is there something else perhaps that is not installed on our BW system? Do we need to install a language set or something?

Thanks,

Chris