Divert/plumb bathroom sink to black tank

[rich.dev]

We ordered our LE2 with the Nature's Head "composting" toilet and I want to divert the urine to the black tank (many posts/videos about that). However, I also want to divert/plumb the bathroom sink to the black tank so it's not only urine in there.

So, my question is, has anyone diverted/plumbed the bathroom sink to the black tank? Sorry if this has been covered in the past, I searched the Oliver Forums as well Google "site:olivertraveltrailers.com forum divert bathroom sink to black tank" (as suggested by mossemi), but no luck! I know I can transfer the grey water through a portable pump with inlet filter into the black tank rinse port, but that's an extra step I would like to avoid!

Thanks, 
Richard