Semen married Maria, a daughter of Jonas Goštautas. In the mid-1450s Goštautas planned to depose Grand Duke Casimir IV Jagiellon and to install his son-in-law Semen Olelkovich. Semen inherited the Principality of Kiev, but after his death it was converted into the Kiev Voivodeship. His descendants continued to claim the rights to the region, but the voivodeship was ruled by appointed officials (voivodes) from other noble families. The loss of Kiev could be attributed to Olelkovich's faith (Eastern Orthodoxy rather than Catholicism) and their close kinship with the Grand Princes of Moscow, who threatened Lithuania's eastern borders. However, the Duchy of Slutsk–Kapyl was not converted into a powiat and remained in the family's hands. Disappointed by prevailing politics, Mikhailo Olelkovich organized opposition to Casimir IV and even attempted a coup in 1481. The plot was uncovered, possibly by the voivode of Kiev Ivan Chodkiewicz, and Mikhailo was executed. In 1471, Mikhailo had also been involved in a brief alliance when Novgorod Republic invited him to become its ruler in a bid to break away from Moscow's influence. However, the attempt ended in a decisive defeat at the Battle of Shelon.