We can utilize a HashSet data structure to store the unique transformations. For each word, we can generate its Morse code transformation by replacing each character by its corresponding Morse code. We then add each transformation to the HashSet to automatically handle duplicates. The size of the HashSet at the end gives us the number of unique transformations.

In this method, we establish a direct mapping of characters to Morse code using a fixed array index, which simplifies the translation process by utilizing the ASCII value difference between 'a' and the current character. We then use the translated words to populate a set directly, ensuring uniqueness of each transformation.