Isn't one option to a buy another ticket in the same name for CPH-SPU? SPU? Split. It reminds me of a geography test in grade school. "A country with a split in it". The answer was Yugoslavia and nobody got it right.

An SAS extra seat anecdote from the 1980s, A famous composer had purchased an extra seat in business. To accommodate a non-rev they put his musical instrument in the cupboard!