In reference to your proposed drawing you show the washing machine standpipe above the laundry tub/wet bar drain. In other posts on this forum, I believe Hackney Plumbing has said he does not do that for the following reason:
Thats what I call a major over a minor. The washing machine pumps alot of water fast. I dont install a major over a minor.
Also what type of fitting are you planning on using at this junction?