I use a lot of shortcuts and haven't seen a way to do that directly (someone may chime in with a way)
BUT - make handles for the groups short and use Nicknames / handles in the address book entries and it will work like a charm. I have assigned my wife the nick name of "VV" I type that in the address line and it will automaically fill it in. Same with groups. I have several handles for groups that work the same way

One thing: if a person is in more that one group and you send to both groups at once, they will only get one email - the bat can clean the duplicates