Help needed with combining 2 itunes libraries

[KayMomto3]

I have one iTunes library on my MBP and another on an iMac that are different. I want to combine them into one (on the iMac) but when I try the songs/videos moved over can't be found by the iMac (have the exclamation mark next to the title). I really don't want to backup to disc to move them over by restoring because the library I am moving is 70+ GB (that's a lot of discs) so I have copied the folder onto a separate harddrive.

How do I combine these libraries? Please give me step by step instructions that a middle aged Mom who has not slept through the night in 14 years can understand

 

[JediMeister]

It sounds like the option in iTunes' Advanced preferences isn't checked to copy to the library when importing/adding. Without that enabled, you can add songs to the library from the external drive, but as soon as you disconnect the drive, neither iTunes nor the computer can find the pathing for songs any longer. Go to the iTunes application on the iMac, go to preferences under the iTunes menu, click on the gear for the Advanced preferences, and look for this:

Also, if the iTunes content is purchased under different iTunes accounts, you will have to authorize the iMac with the account information the songs/videos were purchased under.