Could you cook Chicken Galantine in stock?
There are a couple of ways to cook and serve a galantine or ballotine...roasted on a rack or wrapped in plastic wrap or cloth and poached...so it depends on your recipe.    Whether you serve it hot or cold may also be a factor.  For a hot preparation you will want a crisp skin. So, you will need to consider that. However, to answer your question directly, using stock instead of water, in any recipe, will generally impart more flavor.  Of course, if you are cooking something wrapped in plastic, it would not matter.