Have you contacted Verna Lou Landis? She's in Gallatin Valley, now, but was raised on the Gjerde sheep ranch, and as I recall, "Grandma Gjerde" used to visit her in the summers back in the 60's. There was also a cousin, Scott Gjerde, who would visit.
She or her son, Bill, can be reached by snail mail, probably at:
Verna Lou Landis
General Delivery (Sedan Route)
Wilsall, Montana 59032
I haven't seen them since the 60's; if they remeber me, it would be as Linda Allen, the youngest of Yates Allen's six daughters.