When you share a page layer (source) on a page in another edition, Fred4 normally prompts you to select whether you want replace the existing layer with the source one, or to add a new layer.

Fred4 does it only if the source layer type matches the type of a layer on the destination page

If you click Yes, the existing layer is replaced with the source one. WARNING: Fred4 does not check before replacing the layer whether it contains elements. Ensure that you know what you are doing, otherwise you can loose data!

If you click No, the source layer is added to the list of layers of the destination page.

It is possible to avoid this prompt and predefine the answer. On the Preferences dialog box, under On matching layers drop, select the predefined answer. Ask displays the prompt. Replace behaves as you would press Yes when prompted, while Add behaves as you would press No when prompted.