I'd like to add a laundry sink in, well, the laundry room. The way the room is set up, I can't branch the supply directly from the washer supply (the washer is placed in a corner on the right and the main waste stack is behind the dryer, to left of the corner-bound washer). There is, however, a shower on the back side of the wall from the desired sink location. Is there anything wrong with branching the supply from the shower (teeing it off and continuing a line down the wall)? I attempted to Google the answer, but didn't quite know how to phrase it, thus finding no answer about mandatory terminal locations of water supply lines (or if that was even a thing to begin with).

I can see a potential problem with dominance of hot water to two sources on the same line, but the hot water heater is just feet down the line. The shower is the first thing to get said hot water, so I don't imagine the few times the laundry sink and shower are in use at the same time being more of an issue then the kitchen sink and the shower who's-more-important problem which exists in every place I've ever lived.

I've got drainage sorted out - and really the supply as well - I just want to make sure that branching from what is currently terminal at the shower is a "thing".