@Quazz what you suggest ? to create a VM with 500 GB and during Windows installation to create partitions C and D ?
you might be correct, because I created another Windows VM, with 50 GB, split the C and D equally at Windows installation, captured with FOG having Image Type - Multiple partitions single disk non-resizable and … when I deployed this image to the client, I had C and D, …
BUT, C:\ had 25Gig and D:\ 25 Gig, and another 450Gig unpartitioned space on HDD

FOG 1.5.7 on Ubuntu 18.04 VM in VMware player.
My case:

• created a VM in VMware player with 30GB HDD and installed Windows 10 1803 with single partition
• entered in Audit Mode
• installed Windows ADK for 1803
• installed software (apps, Office, VLC, etc.)
• installed FOG-Client
• created a folder on C:\customize\Win10\ to copy the Windows installation files and a Distribution folder
• import the .wim to WSIM, select the Distribution folder
• created an customize.xml using WSIM, validated, saved in C:\customize\
• run sysprep.exe /generalize /oobe /shutdown /unattend:C:\customize\customize.xml
• create a image in FOG server, having Image Type - Single Disk resizable, Image Manager - Partimage

Now, sysprep runs fine, shuts VM down.
Then I pxe fine, make Full host registration, I capture the image.

Now, when I deploy this image to an HP client, with 500 GB HDD, I get only 2 partitions, the System and C.

My question is, what I’ve missed not having the partitioning like in the unattend.xml file ?

below is only the partitioning section from customize.xml

<?xml version="1.0" encoding="utf-8"?>
<unattend xmlns="urn:schemas-microsoft-com:unattend">
    <settings pass="windowsPE">
        <component name="Microsoft-Windows-International-Core-WinPE" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
            <SetupUILanguage>
                <UILanguage>en-US</UILanguage>
            </SetupUILanguage>
            <InputLocale>en-US</InputLocale>
            <SystemLocale>en-US</SystemLocale>
            <UILanguage>en-US</UILanguage>
            <UserLocale>en-US</UserLocale>
        </component>
        <component name="Microsoft-Windows-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
            <DiskConfiguration>
                <Disk wcm:action="add">
                    <CreatePartitions>
                        <CreatePartition wcm:action="add">
                            <Order>1</Order>
                            <Size>550</Size>
                            <Type>Primary</Type>
                        </CreatePartition>
                        <CreatePartition wcm:action="add">
                            <Extend>true</Extend>
                            <Order>3</Order>
                            <Type>Primary</Type>
                        </CreatePartition>
                        <CreatePartition wcm:action="add">
                            <Order>2</Order>
                            <Size>102500</Size>
                            <Type>Primary</Type>
                        </CreatePartition>
                    </CreatePartitions>
                    <ModifyPartitions>
                        <ModifyPartition wcm:action="add">
                            <Active>true</Active>
                            <Format>NTFS</Format>
                            <Label>System Reserved</Label>
                            <Order>1</Order>
                            <PartitionID>1</PartitionID>
                        </ModifyPartition>
                        <ModifyPartition wcm:action="add">
                            <Format>NTFS</Format>
                            <Label>Local Disk</Label>
                            <Letter>D</Letter>
                            <Order>3</Order>
                            <PartitionID>3</PartitionID>
                        </ModifyPartition>
                        <ModifyPartition wcm:action="add">
                            <Format>NTFS</Format>
                            <Label>Windows</Label>
                            <Letter>C</Letter>
                            <Order>2</Order>
                            <PartitionID>2</PartitionID>
                        </ModifyPartition>
                    </ModifyPartitions>
                    <DiskID>0</DiskID>
                    <WillWipeDisk>true</WillWipeDisk>
                </Disk>
                <WillShowUI>OnError</WillShowUI>
            </DiskConfiguration>
            <ImageInstall>
                <OSImage>
                    <InstallTo>
                        <DiskID>0</DiskID>
                        <PartitionID>2</PartitionID>
                    </InstallTo>
                </OSImage>
            </ImageInstall>
            <UserData>
                <ProductKey>
                    <Key>xxx-xxx-xxx-xxx</Key>
                </ProductKey>
                <AcceptEula>true</AcceptEula>
                <Organization>xyz</Organization>
            </UserData>
        </component>
    </settings>
    <settings pass="oobeSystem">