multiman supports mounting iso on ntfs partitions however ntfs partitions are not fully supported by mmOS.
There is a PFS driver bringing read-only ntfs partition support, some usb devices are not recognised though.
Iirc the PFS driver can only be used in regular multiman mode (not in mmCM for Cobra), you can find the option in the mmOS menu.
If your USB device is not detected by mmOS when you enable the PFS driver, you could try adding a USB.CFG file in the multiman folder with the disk device ID in it to help the PFS driver identify the disk & mount the ntfs partitions on it. You can get the device ID from Windows in the device properties. But in my experience, when a disk isn't automatically detected by the PFS driver, adding the id in USB.CFG had never seemed to help.
All other file managers in backup managers like Irisman, Managunz, webMAN-MOD, sMan etc.. use a full NTFS driver library & offer read/write ntfs support. I would use them instead to manage files if I were you.
Btw /dev_usbXXX mount points are usually reserved to USB FAT partitions.
Backup managers use different mount points for NTFS partitions.