DIY Doctor UK DIY Forums

I want to add a basin to our downstairs toilet. The toilet is connected to the vertical soil pipe in the wall and I can't get access easily. The outlet from the toilet runs along the inside of the wall for about 2000mm before entering the wall(and soil stack), with a drop of 1:40. Can I break into the toilet outlet pipe using something like a boss adaptor and feed the basin waste into it?

Thanks