I'm asking the question primarily because I suspect there is such a word and I forgot it. An example sentence :

The new policy was adopted by the company to simplify the handling of temp workers. It increased overall security as a side effect.

The event is a policy change. The advertised outcome is simplifying some procedure. The incidental outcome is an increase in security. Thus, 'incidentally' satisfices.

It incidentally increased overall security.

However, this word implies that the side effect is accidental (more specifically, incidental :-)) rather than by design. I'd like a word which expresses the idea that the incidental effect was in fact sought-for, and that the advertised outcome for the event of which it is an outcome was put forward only to encourage the occurrence the event, rather than for itself.

If the incidental outcome is sought for by one stakeholder / the narrator in my sentence -- whilst other stakeholders believe the only desirable outcome is that which is advertised (here, simpler temp staff handling), what is a good word to qualify the 'secretly' desirable outcome?

In the case of my sentence, it is already implied that the narrator sees the security outcome as the valuable one (from prior context in the text). Thus, it is acceptable to simply note that the incidental outcome was sought for intentionally. A close concept is French would be the word 'accessoirement', but I don't know if 'accessorily' is in common use.