Well, there is an app that's pretty popular here at this forum: Mail Shot. It comes with a free Lite version (so you can see if you like it or not). With it, you can put a number of people into a group and save the group under a certain name (for example, I have a "Family" group that contains the 6 members of my immediate family).
Then, in your e-mail, you can select that group name and thus have the e-mail go to all the people in that group.
I use this app (well, I use the group I created with this app) all the time and I can tell you that it is quite a timesaver. So, maybe it's something worth looking into? And, is that what you mean? Cause, apps like this are the only way to create groups. The Apple Mail app is limited in that way...
Marilyn