I also suffereded from the issues described by OP.

When I got my Icon through BBVA, I provided them with my existing IB Plus number. For some reason they ignored this completely and created a new IB Plus profile for me. This new IB Plus profile had the added problem of consisting of 9 digits instead of the previous 8, which for some reason Amex doesn't recognise and won't allow MRP transfers to Iberia, but I digress.

Long story short, after many calls to BBVA and Iberia someone finally told me the "new" IB Plus number I had. I had to then merge my accounts by asking IB to transfer the points and close the old account.

The whole thing has been a huge pain in the .... If I went back I wouldn't have requested this card, or at least not from BBVA.