Using the admin theme for editing via 'Steps'

As far as I am aware, the Admin theme settings...

'Use the administration theme when editing or creating content'

Only kicks into action on the paths...

node/add/{NODE-TYPE}

and

node{ID}/edit

but not, for example on the extended path...

node/add/{NODE-TYPE}/STEP1 where this is defined as part of my Form Steps workflow.

I have tried using completely differently-shaped URLs in my steps configuration such as...

/article/create/step1

But no joy.

Finally, if I prefix my path with '/admin' for example, ...

/admin/article/create/step1

Then that works as you might expect but I don't really want to have to do that.

The Form steps features seem to be working just, my issue is only with the theme used.

Can anyone enlighten me on how to get the current admin theme to kick it here?

Thanks