VHD Dynamic Support?

Hello NeroSmart Technologies.
It's about the following product NeoSmart EasyBCD.
And this Thread: Booting into VHD Images

When creating a "VHD" I know you can use VHD or VHDX.
But for creating a Windows VHD, I only can use Fixed size (Recommended).
The virtual hard disk file is allocated to its maximum size when the virtual hard disk is created.

This means when creating a file onto the PC example say 50GB, it creates a 50GB VHD or VHDX and you can mount it, but on you're hardrive it uses the 50GB in question and say example you only use 30GB.

Problem and love to see it fixed:
But what I really love to have is the Dynamically expanding.
The virtual hard disk file grows to its maximum size as data is written to the virtual hard disk.
This means If I use 30GB it uses this 30GB and not the 50GB what I must create above.
This also means a save from 20GB in space.
So I love to use this instead, but the problem is you can't mount this vhd or vhdx file with Windows Installed.
It doesn't get recognized as file, because it can't determine the space onto the vhd or vhdx because it get's expanding or smaller sized.

Is there away to make it work with Dynamically expanding aswel, because then it never use more space then needed.

Hope you can help: