My wife and I are flying United/SAA to JNB from IAH.

We booked this flight using miles and realized we'd rather spend more time in CPT. It doesn't look like I can rebook to CPT using miles and capture the saver rate so we planned on booking a one-way from JBN to CPT and keeping our current reservation.

Two questions:

1) Is this the best option for us?

2) If so, can I link the tickets so I can make CPT the final stop when I check-in at IAH?

Thanks!
Thalmus