Basement toilet: Watergenie - how to connect to main stack
I'm going to be putting a toilet in our basement. It's a Watergenie macerating unit. This unit has the ability to connect two more fixtures to it (sink, bathtub) and pump vertically to a height of 15m approx.
I need a bit of help and advice on where and how to connect the pipe to the main stack.
I've included a labeled picture of the main stack that's in the basement. It's an old house. The washroom and the unit will be located to the right of the pictured main stack about 15ft away.
The output pipe for the macerating unit is only 1 1/2", and my initial thoughts were to tap into the pipe that I have labeled as "main stack vent", as there doesn't seem to be enough space on the 3" main stack itself.
Is this possible, or based on my picture, what are my options as far as where or how to connect it go?
EDIT: it appears that there's a size limit on the pics, and my labels are now very small. I hope they are still legible.