What happened to my contacts list in Yosemite mail

Question

I use to have a pull down list of contacts that I could pick and choose (holding down the Command Key) several addressees.  I can't find that pull down list.  Selecting the + only allows one selection at a time, not several.

Answer 1

Dick2111,
I appreciate your response, but I would hardly call it an acceptable work around.  Your work around only applies if you "pidgeon hole" folks into distinct groupings or contact lists.  I enjoyed and fully utilized the pull down menu in Mountain Lion.  I would enter the BCC field, access the pull down menu of addressees, and double click on each one that I wanted to copy into the BCC field.  Then, with Maverick's, they diminished the ability to double click and finally came up with a "work around" my having to hold down the Command key as I selected individual contacts to move to the BCC field.  That was totally acceptable and I appreciated the escalation and work on the Engineers part.   This work around was only produced after my trouble call was elevated to Senior Engineers.  Now even the Command key option is gone with Yosemite, and the only response I got from Apple Customer Support was to report it via the "feedback" page.  That to me is not unresponsive, but pretty close to it.
It might be an "oversight" but to me is either sloppy programming or perhaps deleting what is thought as infrequently used features to incorporate new features without "growing" the size of the Operating System.
I know i am wrong, but right now I feel it is part of the overall migration plan to an eventually have just one operating system for all Apple platforms, which (tongue in cheek) means if ya can't do it with your thumbs, it can't be important.  I am not sure if there are any third party programs out that address this issue, but I'm not a real fan of replacing Apple core programs with 3rd party stuff, but I may have no choice.  Bummer!