darn, the links don't seem to provide anything for me.
Anyway I did some research and found the following:
https://www.americanexpress.com/uk/c...ation_v1_0.pdf
Page 5, first section...• An insured person must be named on the rental agreement
When I wanted to have them on the agreement once before in Vienna they wanted to charge EUR 30 / day. I thought they were just misunderstanding...
I shall call Amex tomorrow to find out for certain.