In general, there should be little if any relationship between *SPLCTL and OVRPRTF. At the time OVRPRTF is initially executed, there is no spooled file to exert *SPLCTL over. Once the spooled file is created, *SPLCTL may come into effect.
*SPLCTL is intended to give control over spooled files that are owned by others. Please describe the override that is not taking effect. There may be a relationship that involves authorities for an *OUTQ for example. What are the problem users actually unable to accomplish?