Would this situation be considered "Back to Back" or some sort of other disallowed ticketing?

Let's say I book a multi city trip on UA AAA - BBB - CCC - DDD

During my time in BBB, I book another *A partner (using that partner's website to generate a non-016 ticket on that partner's metal) to fly BBB-ZZZ-BBB round trip, and put my UA MP number in the booking to earn UA RDM/PQM in the process.

I'm not booking a separate UA PNR while in the middle of my original PNR's trip, but UA would know about my OAL PNR since they'd be crediting my miles from that *A partner.