I had a small bathroom remodel done after flooding last month. I found out I had a contractor in over his head too late. My situation now is I have a bathroom sink on one side of the wall and the opposing side had him install a utility sink. He put a "T" in the wall parallel and both openings are at the same height. Is that correct? The other issue is he had 1 1/2" lines just ran into the 2 1/2"-3" T and not supported.Each end goes in almost to down drain hole. I see a potential issue of water flowing back into opposing sink as a possibility. Am I incorrect there? Shouldn't the drain lines from each sink be firmly mounted to the "T"? Would I use reducers with threads? Extremely discouraged I got screwed by this guy that unfortunately are the type that give construction workers a bad name when most are honest and hard working. Both sides now have p-traps.