Im doing a bathroom reno which requires some plumbing to be moved the new tub drain now sits where the old toilet drain was the new toilet drain is moved over to the end of the tub which runs underneath the tub in the crawl space. Can I tap into that toilet 3 inch with my tub 1 1/2 drain. Thanks.

Im doing a bathroom reno which requires some plumbing to be moved the new tub drain now sits where the old toilet drain was the new toilet drain is moved over to the end of the tub which runs underneath the tub in the crawl space.
Can I tap into that toilet 3 inch with my tub 1 1/2 drain. Thanks.

You may connect to the toilet drain line only if you run a vent off the tub.
A better way would be to connect to the lavatory drain line and let it wet vent the tub. Good luck, Tom