Hi Kenko -- yes I am a heavy user of Trainline -- have been since it was the original French Capitaine Train.
Well, I unfortunately had to turn away from this back in May -- went home to the States and did a bunch of stuff for my folks, had a lot of work last week, etc etc.
I finally purchased all my tickets this morning (well I purchased some Friday night, I guess).
Of course the cheaper tickets were even more gone by now!
My idea for Heidelberg went by the wayside as there seems to be some issue on my travel dates getting east of Kaiserslautern. So I got tired of messing with it -- I will go on purpose this fall.
So -- I bought:
RT on Thalys Paris --Cologne, I think I got a little discount due to my Carte Avantage.
(Bonus ! I got in touch last night with a friend from graduate school who lives in Cologne to see if she would want to get together dor a drink/dinner whatever the day I am there. She immediately replied yes, so I will get to see her -- first time in more than 25 years -- and meet her husband.)
Then I bought a 25% off Trial Bahn Card for 1st class and bought tickets :
Cologne -- Copenhagen (via Hamburg). This time when I looked to do the split ticketing, it was not any cheaper than the through ticket, so I just went for that.
Kolding -- Cologne, again via Hamburg. Kolding is a Danish town where I will spend a couple of days after my five days in Copenhagen with my brother and his family.
So if I had known what I was doing earlier, or had had time yo mess with this earlier, I could have gotten things more cheaply, I am sure. But I am pretty happy with how I ended up, and while I know most folks on the Forum sing that 2nd class is fine, I have to admit that as much time as I am going to be spending on these trains, I know I will be happier for that tiny extra bit of comfort in First Class.
I am looking forward to my journey and packing I want to rather than how the airline and airport security gods say I must. Champagne in my carry-on?? Yes. !!!! (Indeed, everything is a carry-on on the train ).
Thanks to everyone who offered their advice and expertise to help me out !