Pictures, logos, etc., are normally handled seamlessly by XpressDox.
Sometimes, though, pictures can go missing from the document when it is merged.
This can happen if the same picture occurs more than once in a template. It seems that Word optimizes its memory usage by storing this picture once in the document, as a kind of master version of the picture, and then referring to this master version from the other places in the document where it’s required. Which is quite clever, really.
This can lead to strange behaviour if the first occurrence of the picture in the document is made dependant on some or other condition. If that condition works out to a “false” value when the template is merged, and the master picture is then excluded from the merged document, then the other places that require this picture will not be able to find the master. Usually what happens is that Word puts a square with a red X in it where you would like the picture to be.
The way around this is to make sure that the first occurrence of the repeated picture always appears in the merged result.