Vegetation LOD transitions

[Venom34]

This is a question towards those who have tinkered with vegetation models. I have my own set of tree models that I want to use in my project, with LOD models for performance. The only problem being that the transition between the high LOD and the low LOD happens without any blending, so the high poly tree just pops right in. As you might have noticed, this is not the case for default game vegetation, which nicely blends the 2 models together so there's no pop in. Does anyone know what do I need to do in order to get these transitions to work? I can't wrap my head around it.