As with any other SEO, it will be about making sure the most signals point to the right address, so when they have to decide between the two, they are more likely to choose the one with the strongest signals. With your location, I'd imagine adding your business to Google My Business will carry far more weight than text they find on the page, especially if you list both addresses on your site.
If you are really worried, you could always add the address to another site and embed it with an iframe for your users so that it does not technically appear on your site. However, that would seem over-cautious to me.
Other ways you could increase signals (as always with SEO, only Google know what signals they actually use, and they will change):
- Put the registered address in googleoff tags
- Put the address you want to list in
<adress> tags, but leave the registered one with non-semantic tags.
- Add geotags pointing to the address you want
- The law is unclear, but if it only has to appear on one page of a website, set that page as noindex and nofollow - something like the terms page is unlikely to get you much SEO benefit anyway. Add the main address to other, crawlable, pages.