Xara :: Create Shape With Partial Outline?

I've been using Xara Photo and Graphic designer for about a week now to design some characters for a game I'm working on and in general find it great to use as a freehand authoring tool.

In order to develop a cartoon style, I'm building my characters out of free hand coloured objects with black outlines with cel shading made from partial masked clones of the objects. This works a treat until I come to put two of the objects together and want to erase part of the outline on the topmost object where it meets the underlying one.

I thought I'd found a solution with a tip on the Xara site (at the top of the page here) where you draw the outline portion you want and combine with a second object then break the objects again. This pretty much achieves what I want, I get a filled object with the outline broken where I originally left it, however, things start to go wrong when you attempt to mask clone a part of the object you've created (for example, to produce a shaded portion of the underlying object) as it's still a line and not a shape, so the mask clone gets confused and doesn't cut out the intended area.

This must be a pretty regular requirement, particularly for people creating flash animations, so I'm sure I must be missing something or going about the construction of the image in the wrong way.