How to add more language menus to T3 Blank Theme ?

I'm using latest T3 Blank Theme with Joomla 3.4.4

1. Having three menus (EN, DE and ES), but only the EN menu is displayed on the website.
2. At template Configuration>Navigation>Menu the EN menu is selected and I can't add the DE and ES menus also. Only one choice is possible.
3. I want that the related menu will be displayed at the website, when clicking to another language at languageswitcher link, but only the EN menu links are appearing.
4. When using the languageswitcher, the different language websites are being displayed correctly, only the ES and DE menu links don't appear.
3. Please also have a look at the screen shots of backend and frontend

Thanks for your help - Go