transferring available credit line, need opinions.

[Anonymous]

We have 2 amex business cards (seperately we have amex amzn business, amex gold, amex ed for personal uses):

* blue business plus, 9k CL, 7k BT (now 4.2k), 0% APR offer until july 19.

* blue for business, 20k CL, 0 balance (for more than a year now).

Is there any downside to transfer second card's credit line (then close 2nd card) to the first?

[MyDataMyChoice]

I belive the cards can be combined online (maybe via Chat)

The cards I thought had to be open 13 months. and you can't move over the entire limit... you have to leave 500/1000 on the new card.