Built Lighting Problem

When I rebuilt my lighting, the shadows of the objects were not as good as they were unbuilt and I got a error saying overlapping UVs, which most comes from the forest I have made around my house. Is there a way I can fix this in the settings because it did take me quite a while to build the forest I have built to need to redo the whole thing. Any help?

https://forums.unrealengine.com/community/general-discussion/846-error-lightmap-uv-are-overlapping-by-40