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They have kits for this. I used them to replace two entire bathrooms in a 115 year old home with cast iron lines.

Again with the plumbing vents.
These stick out of your roof and vent sewer gases up above your home.
If they are semi-clogged, you smell it in your home.
When you take a shower, or bath, these...

All plumbing has two lines, one is for water, the other is a vent, for air.

If the vent (metal sleeves over pvc sticking out of your roof) is only slightly clogged with debris (leaves, bugs, dirt)...