Write-optimized DSO ( Technical Key)

Hello experts,

I have the logic - > cube - > write optimized DSO.

Next, I would like to create transformation from Write-optimized DSO to standard DSO. I want to use "Technical Key" ( request, datapakid, record) from write-optimized in transformation to standard DSO ( assigned them to a new Z-IOs - Zrequest, Zdatapakid, Zrecord), but i cannot see them in transformations.

Is any way to use Technical key in transformations ?

Thanks

Martin