Intel advises against using Y16 in an application because it is unrectified and intended for use in camera calibration.
Y16 is also very limited in the modes that it can be used in. And each time that depth is enabled, Y16 mode is 'ghosted out', making it unusable for your goal of streaming both IR and depth. Below are the IR-only modes in which Y16 will operate.
1920x1080, 25 FPS, with depth stream disabled
1920x1080, 15 FPS, with depth diabled
960x540, 25 FPS, with depth disabled
960x540, 15 FPS, with depth disabled
You can however stream IR and depth together with Z16 depth and UYVY IR as an alternative to using Y8 for the IR.
If you are interested in depth post-processing, the paper linked to below may be useful.