As long as you have not turned off to now show them..All A-Z devices should be added without any issues as they are normal filesystem devices.
Is there something special with your setup ? Are they Normal mounted network shared a device letter ?
Is it not in any list or just in some places (Device dropdown, Folder Tree, Device Toolbar ) ?
Are you running MC as Admin ? (network shares are by default not shared between normal and network share session in some Windows setups)