Merge the drawings

[7o7]

There is something wrong with your file 221.idw.dwg , you "audit" it (Files > Drawing Utilities > Audit) and will be fine.

About the sorting, change the defun sort to this:

(defun sort(l)
   (mapcar 'cadr (vl-sort
     (mapcar '(lambda(x) (list (atoi (vl-list->string (vl-remove-if-not '(lambda(y) (<= 48 y 57))  (vl-string->list x)))) x)) l)
 '(lambda(m n) (< (car m) (car n)))))
 )

And what you want to set spacing for? we don't know the dimension of inserted file frame, we can only put them side by side.