Hello, 
I do not know if it's possible to make a suggestion or if there is a place for that kind of topics, but here goes:

When exporting to Unity in my case I need to have the Morph slider for Mouth Opening.
If we use InstaLOD it's not possible anymore to use it, which doesn't make any sense in those two cases:

1- Exporting with Remesher and keeping the original avatar for LOD 0
As the original avatar has all blendshapes, it make sense to have the mouth open shape here as well

2-Exporting with Merge Material option
It's a no brainer in that case as it's the original avatar with only textures merged. I don't see any impact on blendshapes

Could the dev team behind InstaLOD consider this please?

Hi Necka,

It's proposed by other user a while ago. Dev Team has been seeking for a solution, unfortunately, I haven't heard any positive feedback.
https://www.reallusion.com/FeedBackTracker/Issue/Open-Mouth-LOD

I submitted this request ages ago and have no idea what's being done to resolve it.

I'm not sure what the problem is as the level 0 zero avatar should be identical in both
scenarios : if it's exported with or without this option checked.

I really wish Reallusion would be more proactive in solving these kind of issues

good point! +1  
I would like that option to

Hello, just bumping this issue which just put me in an annoying situation : in order to use a Unity asset named Paint in 3d, I need to use the merge material option so the uv can be painted on, but the Merged_Open_Mouth blendshape is absolutely crucial for facial animation so I have to renounce both InstaLod options for now.
While I do not pretend to be an expert in programming or modelling, just like OP I fail to see how exactly either of these options prevent the creation of a single blendshape ?
Really hoping for Reallusion to do something about this, this issue has no reason to exist and must have annoyed a bunch of devs already.