Distance between multiple lines in header of beamer template

this is my first question ;). I have defined a custom header in my beamer template and I want to show multiple lines. Since \\ isn't available in beamercolorbox I had to use \newline instead. The problem is that I cannot define a distance between the lines! I cannot use \vspace or another \newline.

Any idea?

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If you are willing to manually justify the header content, then the stackengine package allows syntax such as \stackunder[spacing]{top line}{bottom line}. –  Steven B. Segletes Feb 20 at 18:57