The only thing about her that looks mildly Pekingese is her muzzle and what appears to be an underbite. However, some Tibbies also have this distinctive underbite. As well, it was mentioned that Pekes have very short very stubby legs. It doesn't seem to fit Mocha at all. She's such a leggy girl; I'm hard pressed to say she might be part Whippet/Iggie.

Therefore, I'd have to go with Tibbie X Sheltie. My guess is that she's made up of 3+ breeds because she has a bit of a leggy "Spaniel-y" type that I can't quite put my finger on.

How much does Mocha weigh and how tall is she? I think a head shot would also help determine whether or not she really is part Pekingese/Tibbie.