How to handmake the lightmapUV for LOD+1 models

Can I made by hand and then import the 2ndUV for LOD+1 models.Or I have to generate it in UE4 Editor.If I don’t make any LOD1+ 2nd UVs,is it set like that the model at this level of LOD cannot be baked into any lightmaps and only shows a dynamic lighting effects.