iTunes batch key word assignments -Help!


Greetings everyone.

I don't see this great question addressed anywhere...

How can I batch-add key words into some field in the ID3 tag, without erasing what's already there?

For example, say I want to add key words (at various times) to the Comments field (or the Groupings field or any other field), for search purposes. Batch processing of tag info obliterates what's already there. But if I have a folder of hundreds of Latin dance songs, I'd like to batch-add the word LatinDance into the Comments field (or some other field) so that it is an additional piece of info--not to erase everything else already there.

Sure, I can do each one manually, but I have 28,000 songs!

See, a particular song might get the "LatinDance" key word added at one time, and then later I'll want to batch-add the word "Instrumental" at some point, and then later still, I might want to add the key word "WeddingSongs" or etc.

If this is not possible, sure seems it SHOULD be!

Note that I cannot even pick my largest category of files and batch add a key word even ONCE to my Comments, because many of the Comments fields already have info in them, and batch adding would erase all existing data.

Any advice?

Many thanks,