Kitchen waste into existing soil stack?

As part of a refurbishment project I am having a new kitchen fitted in a small terraced property.

The new kitchen design moves the sink from its current position against an outside wall to an end wall. It has been suggested by the kitchen supplier that waste water from sink and washing machine could be connected to the existing boxed in soil stack which runs from the bathroom above down through the kitchen in a corner.

In theory this sound good to me but I have some concerns. First is it allowed secondly is it such a good idea?

yes good idea and its allowed.

Wow, a reply before the ink had time to dry

Thank you seco services

whats it into now a gully trap outside ?

Not really familiar with terminology however I think the answer is yes. Similar to this but waste from sink sited above drain not connected as in this pic.