Thanks to all. I tried just having a cabinet in the project, but the result was the same. Editing the sink outside of the cabinet works, but the sink then becomes a stand-alone object which then can't be properly placed in the cabinet. katalyst777 Thanks for the info. It is, as I suspected, not a supported feature in Interiors. I can live with what I have got, if it costs over $100 to fix it!
I am trying to alter a sink after it has been put into a cabinet. I read in the help and on this forum that using TAB or Next will eventually highlight the sink, so it can be edited or deleted. This technique does not work for me, I just end up highlighting the room. Is this feature not available in Home Designer Interiors? At the moment all I can do is delete the cabinet and start again with another sink. I have the same problem with ranges.