Zend certified PHP/Magento developer

Add Partition Table to existing vhdx partition image

I have images of single paritions (not full disks) in vhdx format. I want to create VMs with Hyper-V with them. Since the images are only partitions the machines do not start.

How can I add the disk header or merge multiple vhdx partitions to a singe vhdx disk with header.

Notes: I have 2 use cases:

vhdx imags from WindowsServerBackup(/WindowsImageBackup)
linux ext4 partition created with dd from lvm snapshot & converted with qemu-img
I know the partition sizes since the source servers have to be running