If more than two heat pumps are installed together, it is sufficient that the separate space heaters are labelled with a product label. The dealer can of course calculate the expected performance of the package and include that in the offer (but not on a package label as this combination is not covered by its definition).
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.