I have XXX-FRA-LAX flight coming up. The trip is booked with UA and I have LH booking reference. FRA-LAX upgrade to J is at $840 on LH site. If I were to pay for this upgrade, will I get UA PQP for this? I have never paid for upgrade on partner metal on UA issued ticket, and hence my question.

I do this route once, sometimes twice a year. I have missed FRA-LAX connection because of delayed inbound to FRA and general FRA tardiness. Its not much of an issue since there is a second FRA-LAX 3-4 hours later. If I were to upgrade, and take the second FRA-LAX, will I get either get accommodated in J in the later flight or get a refund? Basically is there a chance I will be out of $800 and fly Y in the middle seat?