# Argument completions for string sequence

I want to add completion for string sequence like

addCompletion[expr___] :=
FEEvaluate@FEPrivateAddSpecialArgCompletion[expr];

list=Alphabet[];
f[x__String]:=(
{x}(*some codes here*)
);


Here addCompletion is from Argument completions for user-defined functions, and list stores some long strings that can be modified by some other functions.

But now only the first argument of f can be completed. I tried (and am not satisfied)

$fcompletion=4; f[x__String]:=( addCompletion["f"->Table[list,$fcompletion]];
{x}(*some codes here*)
);


Is there a method of completion adapted for __?