Changing network configuration for all VMs in VirtualBox - powershell

Question

I've a problem with forceing NAT mode on network cards in all VirtualBox machines. The only solution I have found is to replace the code in the configuration file located in the C:\Users\USER\VirtualBoxVMs\VirtualMachineName\VirtualMachineName.vbox.
Unfortunately, I cannot simply replace these files because each user has different settings (such as the name of the VM)
I have to replace the text in the
<Adapter>...<Adapter> tag. Doing it on one computer for one user is not a problem. I can't deal with the fact that I have to do it with a script on multiple computers for all users. So far, I've managed to do something like this, and I don't know what to do next.
$InputFiles = Get-Item "C:\Users\*\VirtualBox VMs\*\*.vbox"
$OldString = '<Adapter ...various computer-dependent variables...>
...
...
</Adapter>'
$NewString = '<Adapter ...various computer-dependent variables...>
<NAT/>
</Adapter>'
$InputFiles | ForEach {
(Get-Content -Path $_.FullName).Replace($OldString,$NewString) | Set-Content -Path $_.FullName
}
Another complication is that when saving changes, everything is saved in one file for all users, i.e. all settings from all machines on a given computer as one file.
Unfortunately, VB does not store such values in the register, which makes it very difficult. Maybe there is another, easy way?
EDIT: Sample VBox config file
<?xml version="1.0"?>
<!--
** DO NOT EDIT THIS FILE.
** If you make changes to this file while any VirtualBox related application
** is running, your changes will be overwritten later, without taking effect.
** Use VBoxManage or the VirtualBox Manager GUI to make changes.
-->
<VirtualBox xmlns="http://www.virtualbox.org/" version="1.15-windows">
<Machine uuid="{1d96510c-97ce-4671-a1df-3f08c7d2b2c7}" name="TEST" OSType="Windows7_64" snapshotFolder="Snapshots" lastStateChange="2020-05-04T09:56:34Z">
<MediaRegistry>
<HardDisks>
<HardDisk uuid="{eab23143-54ec-4f7d-822d-a56bf90a58bb}" location="TEST.vdi" format="VDI" type="Normal"/>
</HardDisks>
</MediaRegistry>
<ExtraData>
<ExtraDataItem name="GUI/FirstRun" value="yes"/>
</ExtraData>
<Hardware>
<CPU>
<PAE enabled="false"/>
<LongMode enabled="true"/>
<HardwareVirtExLargePages enabled="true"/>
</CPU>
<Memory RAMSize="2048"/>
<HID Pointing="USBTablet"/>
<Paravirt provider="Default"/>
<Display VRAMSize="18"/>
<VideoCapture fps="25" options="ac_enabled=false"/>
<RemoteDisplay enabled="false"/>
<BIOS>
<IOAPIC enabled="true"/>
</BIOS>
<USB>
<Controllers>
<Controller name="OHCI" type="OHCI"/>
<Controller name="EHCI" type="EHCI"/>
</Controllers>
</USB>
<Network>
<Adapter slot="0" enabled="true" MACAddress="MACAddress" cable="true" type="82540EM">
<NAT/>
</Adapter>
</Network>
<AudioAdapter controller="HDA" driver="DirectSound" enabled="true" enabledIn="false"/>
</Hardware>
<StorageControllers>
<StorageController name="SATA" type="AHCI" PortCount="2" useHostIOCache="false" Bootable="true" IDE0MasterEmulationPort="0" IDE0SlaveEmulationPort="1" IDE1MasterEmulationPort="2" IDE1SlaveEmulationPort="3">
<AttachedDevice type="HardDisk" hotpluggable="false" port="0" device="0">
<Image uuid="{eab23143-54ec-4f7d-822d-a56bf90a58bb}"/>
</AttachedDevice>
<AttachedDevice passthrough="false" type="DVD" hotpluggable="false" port="1" device="0"/>
</StorageController>
</StorageControllers>
</Machine>
</VirtualBox>