Ohhh what a lovely dog !! Purebreed yorkie or not she's as cute as a dog can be
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It looks like she has wiry hair, I knew one schnauzer/silky terrier mix that had the same hairtype, she got long hair with the age but not very long, just the cairn terrier length a bit longer and it was a bit harsh to touch it (like on a wire haired dog).
Propably she will get a little bit longer coat not much, you could maybe put bows, the girl i knew who owned the schnauzer/silky mix she could put bows in her