Back in Hearthbreakers they were credited as Ma Pie and Pa Pie. Later on he became Igneous Rock. Then he was finally Igneous Rock Pie officially, although Derpi doesn't recognize that yet. I suppose I'll alias it in.
I like Mau for the sphinx, its an Egyptian cat and I think also the ancient Egyptian word for cat. As for the others, how about Cirrus Breeze and Flit De Mure for Fluttershy's parents and Dandy Lion for Trixie's mom. Though looking through the other suggestions I could also get behind Nimbus Breeze and Posey Shy for Mr. and Mrs. Shy