Oh, most certainly. (I didn’t say it was an organized system) That ad hoc system lent itself very well to assimilating and romanizing local beliefs as part of conquest.

‘Subjugate’ probably wasn’t the right way to frame it. It allowed conquerers to so say “Oh, that sacred tree spirit, that genius loci that you venerate? Yeah that’s one of ours; its a dryad. So we’re just gonna put up a Roman shrine to that dryad right next-to/around it. Don’t you worry! You can keep worshipping it. Just remember that is a Roman thing that you’re worshipping, not something else. Oh! And while your doing that, if might behoove you to consider that [my patron] a proper Roman god, might be more capable of helping you out than these dinky little nymphs you’ve got round these parts. You can tell they are more important because the temple we built is bigger than the shrine for that dryad”