I installed a fan/light to replace the existing light. I would like it to work off the existing switch (both together). I can't seem to get the wiring correct, even though I drew a sketch. The switch wire has 4 wires (tan, red, black, copper), the main is 3 (white, black, copper), the fan/light has 4 (2 whites, blue, black), and the main (I believe) continues to the bedroom. The second switch goes to the sink light. I have tried several combinations - the fan comes on without the switch when I turn on the breaker, or the breaker pops off. The sink light doesn't seem to work anymore. Help

Hey folks, I'm hoping someone might be able to help me out. I want to add a light in the stairwell going down to my basement. There is already a switch on the wall when you open the basement door. That switch controls all of the lights in the basement already. In the box with the switch is a black wire and a white wire. I would like to add the additional light so that the switch that is already on the wall will continue to turn all of the basement lights on as well as the new light i'm installing. How do I connect all of the wiring??? So...in the box right now is a single pole switch with black and white wires (both connected). Coming from the newly installed light...I have a black and white wire ready to be connected. I tried connecting them already by doing black to black and white to white...however what was happening was that when the basement lights were on, the newly installed light was off. Then when I turned the basement lights off, the newly installed light was on! Can someone please help me out????? Thanks in advance.