I'm remodeling a 1955 rancher. I have access to the basement below and the attic above. Currently I'm in the existing half bath and am adding laundry equipment to it. There is an existing 3" cast iron wet vent that has a toilet tied into it (3 x 3 x 3 sanitary T approx 2' run) and the sink tied into it above the toilet tie in (3 x 3 x 2 sanitary T approx 3' run). Can I tie the washing machine into the same wet vent? If so it would be approx 2 1/2'. If allowable, would I use a double sanitary t/sanitary cross or put sanitary Tees above each other?

Thanks for the help - Mike