I called the DFS and asked them how in the world someone should know of these new frequencies.
This switch has been scheduled for decades, yet there is no organised way of information transmission.
T‌he best way is to call FIS and ask them for advice, yet these frequencies can't be dialed in often with the spacing set to 8.33khz.

H‌owever, The DFS Manged to publish an update on the frequencies of most German small air fields:
https://www.dfs.de/dfs_homepage/de/Services/Customer%20Relations/Kundenbereich%20VFR/05.03.2018%20-%208,33%20kHz-Umstellung/AIC_VFR_02_18_15MAR2018.pdf

I‌t may require a user account , therefore I'll try to attach the file and the addendum.

G‌ood flights. If anyone has the new frequencies for the German FIS sectors to share, let me know‌
‌‌‌Since these frequencies had been published by such a late time, I don't think they'll make it into the printed maps. The official publishing date for those is‌ end of March.

I‌t is like last year when the Czech republic moved to the 8.33 channel spacing - no map had the new frequencies, only SKYDEMON was up tpo dat!
T‌hanks SKYDEMON , this is the way to go.‌