From Xojo Documentation
Returns a FolderItem based on the string passed to it.
If the string indicates a relative path, the current FolderItem is considered its reference point. If the string passed to it is absolute, then the current FolderItem is ignored when resolving the path.
GetRelative returns Nil only if there is not sufficient information in SaveInfo to construct a FolderItem (e.g., using a relative path that causes the parsing to descend below root level).