It is not a $1,000 CL, it is a temporary limit of $1,000 until the physical card is issued and the cardholder verifies it. Simply an anti-fraud device, but designed as a come on to get people to use it on a DL ticket right away.

Rather than worrying about all of this, why not:
1. Purchase 2 tickets on the new card.
2. Purchase the third ticket on another card.

Why do you care about whether the three tickets are booked into the same PNR? If you could identify the benefits you see from that it would be helpful to know as that might suggest a different approach.