Instead of pulling 1 carry-on (e.g. the following 55 cm Spinner by Samsonite) and 1 full-size checked (30") suitcase separately, one with each hand, how can the carry-on be attached or fastened to the checked suitcase, to facilitate pulling both with one hand and freeing the other hand?
One possibility is to purchase Luggage Sets used by flight crew, but I wish not to spend extra money to do this when I already possess many suitcases.