Just sharing a few things about SW I was unsure of and thought might be helpful for others:
If you have two companion passes, it is possible to book both CP earners on the same confirmation number. Then go to each CP earner's account, find the trip and "add companion" using their designated companion. Doing it this way, you end up with 3 confirmation numbers instead of four. But, what's great is that only the primary confirmation number (that of the CP earners) is time sensitive for checking in. Both designated companions will be linked in the boarding positions next to the CP holders. You do have to go in and check-in each of the other confirmation numbers as a formality to obtain boarding passes, but it isn't time sensitive.
If you are using airline incidental credits, SW taxes do post as separate transactions for Amex, even if booked in one transaction. I posed this question yesterday and wanted to confirm my experience. The charge was lumped together when it was pending, but then posted separately.