How To Add Names to Distribution List

Question.

How do I add Names to a Distribution List?

When I click on add new distribution list I get a window with space for two 
entries - the name of the list and one with distribution list members.

Instead of being able to highlight the names I want added to the distribution 
list, I apparently need to add EACH NAME INDIVIDUALLY!

Some of my distribution lists have hundreds of names and this method is a 
total non-starter.

Is there a way to revert to the old way of adding distribution list members - 
dragging and dropping?

Thanks, Bob.