Dusty Black came to Austin from Houston, to take over the KVET/KASE cluster. He knew of the KFMK calls, and chose them when Steve Hicks accquired 105.7.
(The original filer opened the frequency for Round Rock, but competing filers wouldn't settle, and left the channel unused for more than a decade. When he learned of this Steve Hicks bought them all out, and got the station on the air. It was seperate from the rest of Gulfstar, but run as part of the cluster. )
I had prepared a proposal for a ridiculous music format that violated every rule and consultant's advice for a music station, for a station that might have gone into Houston at 97. I used the calls KFMK in that presentation. I shared the presentation with Dusty, and saw how shocked he was. The calls he had chosen for 105.7 were supposed to be a big secret.
TLdr: Dusty knew the calls from Houston, and chose them for the Round Rock station when Hicks accquired the license.