Backing up, updating and copying iPhoto
I have a new Macbook with Yosemite and want to use my old iPhoto library on it. This is at present on an EHD and I have been using it on an old iMac and I am worried about updating it before backing it up. I have many of the photos on CDs but not all of them. I have a new TM as well, but my iMac is too old to work with it and so I cannot back up the EHD to that first. What is the best way forwards - copy onto another EHD? Update and then back up on the TM? I obviously don't want to put my iPhoto library at risk!
Thanks in advance for your help.
null-OTHER, OS X Yosemite (10.10.2)