Do I need to relocate the shower and open the floor again if I rotate by basement bathtub 90 degree around the drain point?
The location where the tub drain is, typically has an area of the floor where the drain is that is not poured, so the p-trap can be adjusted the final amount for the connection to the tub. You most likely will need to cut out the old p-trap to configure the new one.
I am not certain of the code, but for one sink you can use 1 1/2&quot; pipe for the drain, but since you have 2 sinks, you will need to run 2&quot; pipe. That means drilling 2 1/2&quot; to 2 5/8&quot; holes through the 3 1/2&quot; studs, not leaving much for strength. In addition, you will need to run a vent line to tie back in to the original as well. Vents are to be within 5' of a sink or tub. If the vent comes off the tub drain, you may be in luck, but if it come off the old sink location, it will need to be added. Back at the drilling, you cold notch the pipe, leaving 1&quot; on one side and use a reinforcement piece that guards the pipe from fasteners and strengthens the notch.