Manage iPhoto on external hard disk

Most of my Mac hard drive is filled with iPhoto pictures. I have an external USB hard drive. What to do? Just moving pictures from Pictures/iPhoto Library is not a perfect option as I want to have some newer pictures on my Mac.

iPhoto supports to have two libraries, and I am quite happy with that option. I can copy whole library to external disk and then remove pictures older than a year from local iPhoto library.

However I have two problems: Once I import new pictures, I should copy the whole iPhoto library again (with duplicated files) and also this process should be done manually every time.

I am looking for a smarter option. Do you have any idea?

Try this tool:

http://www.fatcatsoftware.com/iplm/

It allows you to manage multiple libraries, and split, merge, etc.