Simplygon is really the goto app for handling LODS and blendshapes. Of course this is an offline approach and you still have to export your LODS and blendshapes. To do this in engine is I'm sure doable but you're asking a lot from it and I'd imagine performance would suffer as a result. What you're essentially asking for is a runtime wrap deformer which I know would be a huge performance hit. If you already have the exported animation that drives the blendshape data then it should just hook up to LODS with the same track data.
Now I know of 1 game studio that implemented Simplygon into their build process so when game data is exported, the Simplygon API kicks in and produces another asset automagically. But there are some big +/- to that too. My advice, don't try to do it at runtime if you care about performance.