Basically instead of /group invite "Person1" and so forth,It would be "/group invite "Person1,Person2,Person3" Just makes things more conveniant.

1. It's spelled like this: "sentence"

2. Sentence isn't the correct term here. What you are thinking of is "one line command".

3. Also, "convenient". No A's in there.

4. +1 to the general concept

The idea does lend itself to convenience, but the technical realities of implementing something like this could make it somewhat less so. Because names can have almost all punctuation characters in any permutation, it would be necessary to surround all names in quotations to support this (even names that don't normally need quotes). This is because all normal delimiter characters (e.g. commas) are allowable in names and thus couldn't be used to delimit the list of names. Tab-completion does add quotations to names that require them, but tab-completion also doesn't cycle through the multiple possibilities of names. If you get the wrong name on the first attempt, you now have to delete it and try again.

Yea eh..sorry for my poor grammar...

Ignore the grammar police, its a good idea.

Until the devs get to it perhaps a plugin is in order....

"Because names can have almost all punctuation characters in any permutation, it would be necessary to surround all names in quotations to support this (even names that don't normally need quotes)."

No it wouldn't. For example, you could use an algorithm like this:

Check the first character in the parameter string.
If space, move on to the next character.
If quote, scan ahead for next quote and consider all characters between to be one name.
Else, scan ahead for next space and consider all characters between to be one name.
Repeat until end of string.

@Pizzasgood
That doesn't work if the player's name contains a space...

The solution is simple with a plug-in via a recursive loop where you input one name at a time. Just enter the command /invite. Then in the prompt enter one name, and that person will be invited, and another prompt will be given for the next name. End the loop by entering no text in the prompt or by pressing escape.

As a bonus you can even do the following instead if you prefer: /invite "player 1" "player 2" "player 3"

[EDIT] Hmm, even with my solution you still have to enter quotes if the player's name contains a space or possibly other strange characters

Here's the plugin:
RegisterUserCommand('invite', function(_, args)
for _,name in ipairs(args or {}) do Group.Invite(name) end
gkinterface.GKProcessCommand"prompt invite"
end)

"That doesn't work if the player's name contains a space..."

Sure it does, as long as names with spaces are quoted. The point wasn't to avoid quotes, only to avoid needing quotes for the names that don't have spaces in them. Draugath seemed to think that couldn't be done, for some reason.

+1 to this idea.

Also, please simplify /group join so that it implicitly joins the last group invite you received if the player name is omitted.

+1 for someone to make a plugin do this.