It depends what your backup software is...
Option1 Create a new volume on the Nimble, present it to your hosts, create a new VMDK on it for the D drive and configure within windows. VMware based backups (VEEAM) will be able to backup this volume, and Nimble will be able to snapshot it as well.
Option2 Create a new volume on the Nimble, present it to the VM using the iSCSI initiator. Make sure you have 2 storage NICs on the VM and your hosts are configured correctly for multi-pathing. VMware based backups (VEEAM) will not be able to backup this in guest iSCSI mounted volume, but the Nimble will still be able to snap it.
Either option will allow you to grow the volume on the Nimble side and for option 1 increase the size of the VMDK.