Umut's outfit as seen in the final design within TME had been in the works for awhile, most directly inspired by a photograph of Soong Ching-ling wearing a cheongsam during China's Republican Era.
Over time the details of this design shifted, even so, the silhouette remained largely unchanged.
Appearing originally in S&M's first and third chapters on the phone, Umut was planned to be depicted in the second episode during the chapter that eventually became The Mirror Eater.
During this time her design was (thought to be) finalized, resulting in the concept pieces below.
Due to the restructuring of the story and the rewrite, this design would go unused, though is referenced in her portrait as seen in the (yet to be released) post-0.313 S&M.
The origins of her design (and character more broadly) were in a scrapped project known as The Mirror Eater (the name later being reused for TME as it is now). This version of the character would sit on the shelf for a time, until ultimately being split into Umut and Hanusz.
(Bonus: Early Hanusz concepts from TME's (soon releasing) second build.)
The split of the character was a result of the over-developed nature of the original Umut, who would've likely gone under-explored in the original TME plot.
So! End result, two characters and even more stuff to depict–yay…?