OK, I did that, but I had to retyp the link in Domain, not in the URL box, because when I did that the "flash" extension that was there reappered after typing the URL (Copy-paste did not work there).
The results are that I do not get a message from AVG anymore that the connection with coinhave was discontinued, so I hopefully can assume that it was established. In other words cody, your suggestion works. Thanks a lot.