Hello from South Africa!

I am about to give up all my hard-earned Delta status now that I am in SAA's hub. I'm having a hard time figuring out what's the smartest thing to do, mile-wise.

I have a United FF number with a small amount of legacy miles (18,000). I have no SAA miles.

Do I create a SAA frequent flyer number and enroll with them? Do I use my United number? Heck I even have some miles on Brussels.

Thanks for any advice!