Public BigRange As Range
Sub test1()
Dim f As Worksheet: Set f = Sheets(1)
Set BigRange = Union(f.[AC46], f.[AM46], f.[AW46], f.[AX46])
MsgBox BigRange.Parent.Name & Chr(13) & BigRange.Address(0, 0)
End Sub
Sub test2()
Dim f As Worksheet: Set f = Sheets(2)
Set BigRange = Union(f.[AC46], f.[AM46], f.[AW46], f.[AX46])
MsgBox BigRange.Parent.Name & Chr(13) & BigRange.Address(0, 0)
End Sub