Thanks Eric - there's a page about paint before you get to the cushion option.
I did think it might just be easier to add different cushions as items, rather than a 'if cushion selected add $x.xx per cushion' as it seems here.
With eCart, is it reasonably straightforward to have different cushions, and display particular cushions as being available with particular furniture? (I think there are only two sizes, maybe three).
I just don't want to go in and break the whole thing, as I wouldn't be too confident with coding the PHP directly, and I have no idea what the original cart is.
Similarly, if its something that *should* be pretty straightforward for someone to edit who did know about PHP and/or the original cart, then me spending time reinventing the wheel with eCart seems like a long road for a short cut....