Doc,
I would not promote the habit to use vars like $ReDim either, but it seems to work:
Code:

If NOT @LOGONMODE
Break On
EndIf
Dim $SO
$SO = SetOption("Explicit","On")
$SO = SetOption("NoMacrosInStrings","On")
$SO = SetOption("NoVarsInStrings","On")
$SO = SetOption("WrapAtEOL","On")

Dim $ReDim[2]
$ReDim = Split("a,b,c",",")
ReDim Preserve $ReDim[3]
$ReDim[3] = "d"
For Each $SO In $ReDim
? $SO
Next
? "KiX Version: " + @KIX
? "KiX Executable: " @SCRIPTEXE


Output on screen
Code:

a
b
c
d
KiX Version: 4.53 Release Candidate 1
KiX Executable: KIX32.EXE