PPL/CPL test questions

Hi all!

I've been reading here for a long time, but now I have a question for
myself that I want to ask.

I'm from Germany. Last year I have been in the US to begin working on
my PPL. My goal is to get PPL then CPL. I have flown a lot of hours
(over 70hrs), but since I had to return earlier than expected I
couldn't do the checkride any more (but I finished the written with
flying collors). This year I had no time to return, so I have to defer
that to next year. My plan is to finish PPL and after that go for CPL
directly (I'll have more than 100hrs at that time).

The written I took in the US of course is already expired (more than
12 month since I took it), so I have to redo it. I now found out that
there are places here in Germany where I can take the written exam for
US pilot certificates. So before leaving to the US again I can finish
my written here in Germany, and can concentrate on flying in the US.
I'm currently studying/refreshing CPL knowledge, and because I want to
go to CPL directly after the PPL checkride I wonder if I can take both
PPL and CPL written here in Germany before I leave. I know You must
have the PPL certificate before You can get the CPL, but what I want
to know is: can I do the written exam for CPL even when at that time I
don't have a PPL certificate? If I can, I could do both PPL and CPL
written exams here in Germany, and after that can concentrate on
flying and the PPL and later CPL checkride. Is that possible?

Regards

Joe