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.

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.

EDIT 1: on intentionality.

If the incidental outcome is sought for by the narrator in my sentence -- whilst others aren't aware of this outcome or don't value it, what is a good word to qualify the 'secretly' or 'unknowingly' 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.

EDIT 2: on temporality

The concept of 'ulterior motive' proposed by Peter A. Schneider seems to work very well ('ulteriorly increased overall security'). Unfortunately, ulterior has another meaning: after something. Both effects are realised immediately. The same principle rules out 'consequently' from cobaltduck which otherwise would have been the best fit for me.

At this stage, I need to branch the question.

Scenario 1: the incidental outcome is a consequence of the realised, assumed outcome

In that scenario, both ulteriorly and consequently work. I have a slight preference for consequently in that context. As my example fits example 1 better, I'm accepting that answer:

The new policy was adopted by the company to simplify the handling of temp workers. It consequently increased overall security.

Scenario 2: the incidental outcome is a consequence of the change, not of the assumed outcome

The unrealised outcome is effective immediately, not as a conclusion over time of the realised outcome. The word I was looking for is 'coincidentally'. This contains incidentality, and removes the accidental aspect of the word by clarifying that both outcomes co-occur.

I find the notion that awareness of the coincidental outcome was not sought is a bit weakly represented. I could solve this by applying both 'ulteriorly' and 'coincidentally' to the second outcome. But let's keep it simple to digest. My sentence construction says the policy was 'adopted to', thus intent in the outcomes is clear as long as they're presented contiguously within the sentence:

The new policy was adopted by the company to simplify the handling of temp workers, and to coincidentally increase overall security.

I find that sentence remains concise and to the point, but is more precise. Thanks everyone for the help.