Part of corporate contracts is that the enrolled TA is notified of all changes. Some employers want to know this information and so it is supplied by the TA. Most could care less.
Every time you are rebooked in IRROPS or SDC on UA, your TA is being notified.
So, check with your employer, make sure it doesn't care and then proceed. If your employer cares that you fly steerage, even if you are prepared to pay for the upgrade, that is a labor issue between you and your employer.