Do you think that is possible some cards are not able to be verified on Curve due to 3ds ? Or I did not make any sense here ?
No you should be able to add any card on Curve regardless of if it supports 3DS or not. Curve simply don’t request 3DS verification when adding cards.
There are (or at least used to be) some cards that wouldn’t accept online transactions if the first transaction wasn’t 3DS confirmed, but that’s a rare occurrence. By the way I thought Curve supported 3DS for verification, just not for their own cards, but I might be in the wrong here.