If people are happy to work this way, then I don't need to worry about something which works in DAZ but not in Poser.
Sounds like you're getting kind of depressed.
I think I contributed to this problem. Or maybe caused it.
Because I never use the document window it didn't occur to me what would happen with the base figure body parts set not visible.
So if this character you're currently working with was made by the BuildHybridFigure.py script it could be changed.
The body parts could be set to not visible in render instead, which means that you would still see Harry's fore-legs and cannons etc in the preview, and the selection would work normally. But those body parts would not show or cast shadows etc. in the render.
It's not the same as the property 'Set Visible in Raytracing' or 'Set Visible In Camera' and there's no way to change it in the properties panel.
It would look pretty strange in the preview though.
Don't know what people who buy it would think.
Well, it must have been like that at some point so you probably already know what it looks like.
So, I changed the script that builds the hybrid figure.
It still has the same name so you could just replace the old with the new.
Maybe rename the old one BuildHybridFigure_bak.py and put the new one in the same directory and see what happens.
Think about what kind of impression customers would get seeing both sets of body parts in the preview and how to explain the way it's going to work in render.
It seems like maybe a lot of people work in the document window so here's the alternate script.