I cannot help with current family connections, but can propose a couple of possibilities as your ancestors.I found the following names as emigrants from Hessen Darmstadt to Russia in the year 1766.
(1) Johann Caspar Kraus, from Freienseen, Hessen Darmstadt. He married his wife, Eva Volck, on July 17, 1766. (2) Johann Jacob Jacobi, from Vonhausen, Hessen Darmstadt.
I do not know if they colonized Doenhof. You might check with Richard and Judy Deffler, Fr. Collins, CO.They are the Coordinators from the village of Doenhof for the AHSGR website.Doenhof was Gololobovka, but apparently is now named Visakoye (BbICOKOE).At least that is my conclusion, after comparing Stumpp's Karte der deutschen Siedlungen in Wolgagebiet, with a fairly detailed Russian road atlas.
My wife's grandfather, William Lind, was born in Doenhof, and lived in Windsor, CO.