I botched that last question by omitting a "not" (so I was kind of assuming you weren't going to do a direct turn-around). I get that the "one PNR" provides some additional security in case there's any unexpected change in the airline's schedule etc. but in this case (travelling between capitals being one of the reasons) you should be safe. However do try the hotline if you're still semi-curious as to if it's feasible to book it as one PNR.