I do this quite a lot when I’m travelling on business to SA. I nest a JNB-US-JNB Flight in J and GUF to F, adding stopovers in London. I then use the outward leg of this trip as my return for the business trip, meaning I’ve started traveling on both tickets, which makes future changes easier. At one point, during a sale last year, I got Miami for £2100, with UK stopover taxes adding another £300, so £2,400 all in. I’m using one of those to go to Miami with friends this weekend. The good thing is that the ticket only costs R1500 to change, so you can move it around to suit.