I think retrocrediting might work. But let us see what others will say.

The risk is that if you want to use FTL benefits during your flight, you might need to show your card. Some agents will helpfully add it to the reservation at this point, without asking it, and then retro-crediting is no longer an option.

(note that CPH-ZRH should give 1500 EB points one way if you fly in economy on SK... this might make reaching EBG easier than you anticipated)