I ran into something similar the year before last. I tried to do DFW-AUS x3 in the same day on separate tix, but ran into issues booking online. When I called, they wanted to charge me the phone booking fee.

So I just did two tickets: a DFW-AUS-DFW, then nested in an AUS-OKC-AUS (which stops in DFW). Same miles/segs, only two tix (both legit for web booking), and no fees.

I did have to call AA, with my stubs, to get a couple of the repeat legs to clear.