Rough piping a new upper bath

I am roughing in new pipe to a new space upstairs which will be a 3/4 bath. Each fixture will drain individually...4" for toilet,
2" for shower, 1 1/2 for lav sink. I have a "secondary" 2" vent pipe nearby all the future fixtures (within five feet). This currently only vents the exising downstairs shower. May I tie my vents to this 2" and if so may I use combo wyes to do so????

Thanks, Todd