If your agent booked the reservation on SABRE, you may view the booking on www.virtuallythere.com and by entering your PNR-Reservation number (SABRE) and your last name, you will be able to view the reservation.

You will note however that your flight will read UA xxxx followed below with a remark like Flight is operated by Luftansa.

Again, we attest ... Lufthansa has no access to your booking information. Not even by pulling up a passenger list - only if you are actively booked on an LH flight number. But since you are not, all information must be relayed through UNITED until the day of departure and at check-in at the Lufthansa desk.