I have a washing machine that I need to tie into the main stack. It is not up to code right now, as the 2" washing machine drain pipe ties into 1 1/2 inch sink drain pipe, then drains in the main stack. Is there a simple fix of removing the 1 1/2 pipe from the fitting and replacing with a 2" fitting at the main stack. When I eyeball the "y" at the main stack, it looks much bigger than the 1 1/2 pipe entering. Whaddya think?