How to replace a file in Finder

Question

I am trying to back up my iPhoto library, which lives in an external hard drive (My Passport) to my Seagate external hard drive. Usually, I can go in Finder and drag and drop the most recent Library over-top of the backup. A pop-up will appear asking if I want to replace the existing file (yes) and the backup takes like 5 or 6 hours... I have 300 GB of pics.
With OS X Yosemite, when I drag the file and drop it in the backup hard drive, it doesn't recognize that there is already a file with the same name, so it tries to make room to add the new library, when in reality I want it to replace the existing (outdated) backup.
I downloaded this for the Seagate external, which hasn't proved useful http://www.seagate.com/support/external-hard-drives/desktop-hard-drives/backup-p lus-desk/ntfs-driver-for-mac-os-master-dl/
and I tried holding down Option, and Command, then dragging... nope. I can't figure out how to get it to replace, or merge, the files. It just tries to keep putting it in as a separate file.
Please help! 

Answer 1

OS X cannot write to an NTFS formatted drive. Whatever driver you got from Seagate probably doesn't work with the version of OS X you have. Is there any reason you could not reconfigure the drive for OS X? If you can the first thing you will need to do is to reformat that drive to MSDOS (FAT.) It's best to do that on a PC, but you can try reformatting it on your Mac using Disk Utility and setting the Format type to MSDOS. It may take a couple of tries. Once you get it formatted for FAT, then you can repartition and reformat the drive for OS X.
Drive Partition and Format
1. Boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button.  When the menu bar appears select Disk Utility from the Utilities menu.
If you are preparing an external or a non-startup drive, then open Disk Utility in your Utilities folder.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area.  If it does not say "Verified" then the drive is failing or has failed and will need replacing.  SMART info will not be reported  on external drives. Otherwise, click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.
Steps 4-6 are optional but should be used on a drive that has never been formatted before, if the format type is not Mac OS Extended, if the partition scheme has been changed, or if a different operating system (not OS X) has been installed on the drive.
If you need to use the drive on a PC, too, then I suggest using NTFS 12.1.62.