Extending Fiori oDATA service

Hi,

I'm trying to extend Fiori oDATA service SRA017.

I'm trying to add more fields to ProductAttributes Entity, there is Customer Extension Include  SRA017_S_SO_PRODATTR_INCL for sttructure SRA017_S_SO_PRODATTR, I canno edit it, it asking me for access key from OSS, am I missing something? Because std. include structures can be edited without registering object on OSS...

Thanks Jiri