I'm replacing a shower/tub combination with a shower that will drain where the tub/shower used to drain and a new tub on the other side of the bathroom. I'm also removing one of the two sinks in the bathroom. Can I safely drain the new tub into the sink drain I no longer need (or into the main drain reasonably close to where the old sink drain entered). Do I need to worry about enough vents? The entire bathroom is 12 X 8. The shower is in the SE corner. The new tub will be in the NW corner. Sinks are along the S wall. Drain pipe runs pretty much down the S wall. Foot tub will be almost over the drain pipe.