It seems quite an impossible task to transfer the points.
One thing that occured to me is to use your Finnair Plus account for earning Priority Club miles. Finnair is quite generous. 500 points per night and not 500 miles per stay. Finnair also participates quite often in Priority Campaigns like double miles etc.

Well, with 10 000 points you will only get an oneway upgrade within Europe. 20 000 points would give you a hotel night, rental car or domestic flights in the Uk, Finland and probably in Spain. Or points to transfer back to Priority club. 20 000 Finnair Plus points may be transferred back to 40 000 Priority Club points --> four nights at Holiday Inn express worth about € 400.