Hello All,
thank you for the responses. For someone who has no clue, it provides a lot of information. I hope to follow them scrupously. I hope to travel by lufthansa. I hope to keep a gap of 3 hrs at best.

Another ignorant question, on the way back from CDG to FRA does one clear
immigration, customs and security at CDG or if it what happens where?

any other suggestions are most welcome.

Once again thanks.

regads