UR28M Line Input?

I am evaluating Steinberg UR28M as a small remote broadcast mixer, connected to either a laptop or iPad running stream encoding software. Can someone please help me understand the function of the 2TR IN 3.5.mm stereo input? The User Guide states “The input signal at 2TR IN flows only to MIX 1 (page 33), and not to the computer.” However, the mixer schematic shows 2TR IN feeding BUS1/2, which feeds MIX OUT 1/2, which can merge with DIRECT OUT 1/2 into the DAW, presumably on a laptop.

This appears to be the case for non-iPad usage. A second schematic for iPad usage shows DIRECT OUT 1/2/3/4, with no loopback available from MIX OUT 1/2.

In short, I want to be able to feed 2 microphones (for DJ and host), a stereo stage mix (for the live event), and a stereo music playback deck (for event breaks) into the stream encoder.

Is this possible with UR28M? I’m guessing that a laptop will work and iPad will not due to lack of loopback support. Thanks for your assist. Sky