Help with washer/lav drain connections

[Squints2See]

I am moving my washer and re-plumbing the standpipe and adding a sink. My current plan is to have the sink drain straight down like the standpipe is currently and tie into the 3" line running in that joist cavity in the basement. But then I got thinking it would be simpler to tie into the drain for the standpipe as proposed in the picture. I am also planning on running a vent on the lav. just like I'm doing on the standpipe and will tie them all together 6" above the flood rim of the standpipe. So my questions are:

Could I tie into the standpipe drain as proposed below or do I need to continue straight down to the main drain as originally planned?
If I can tie in to the standpipe, should I still make the lav drain have its own vent of the trap arm or can it share the vent on the standpipe?

Green represents vents and the red represents the proposed drain connection.

 

[frodo]

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[Squints2See]

So Frodo,

Looking at your pic, it looks like that is what I am proposing, am I right?

I don't know what the CO in the pic stands for though.

So you are saying that I can tie the lav drain into the washer drain below the sanitee as long as I have a separate vent on the lav and I can tie it into the vent for the standpipe 6" above the standpipe which is the highest fixture?

 

[frodo]

So Frodo,

Looking at your pic, it looks like that is what I am proposing, am I right?

I don't know what the CO in the pic stands for though.

So you are saying that I can tie the lav drain into the washer drain below the sanitee as long as I have a separate vent on the lav and I can tie it into the vent for the standpipe 6" above the standpipe which is the highest fixture?

yes,,,,you have it figured out

 

[Squints2See]

Thank you much!

 

[havasu]

Clean out?////

 

[Squints2See]

Clean out?////

Where would it go?

 

[frodo]

in the vent pipe ABOVE he washer..