ok - I think I understand technically what you are trying to achieve.  This is what you could do:

1. I think your package is DE-TR so I'm working on that basis
2. Extract the xlf files from the WS package and change the target language code in the xlf file to EN
3. Translate the new XLF file anyway you want (Google if that's your preference)
4. I would save these into a TM as you could use the results in your DE-TR project afterwards by adding the DE - EN TM as a read only TM through AnyTM.  Probably a better reference tool that way.  But if you prefer Excel then I'd use the Export to Excel application from the appstore to export the entire translated file to Excel and would not copy/paste every segment manually (but you can if you want!)
5. Then open the original WS for translation, add your DE-EN TM using AnyTM and add Google if that's what you prefer for the DE-TR translation.

Unknown said:

By the way, ws packaes cannot use GOOGLE API.

Yes they can.  See other post - https://community.sdl.com/product-groups/translationproductivity/f/90/p/14870/53089#53089