So I think everyone here basically knows who Peter the Great was but I don't know if all that many people remember his older brother and co-ruler Ivan V. Ivan was the youngest son of Tsar Alexei and his first wife Maria Miloslavskaya and was basically the Carlos II of Russia (physically and mentally disabled); still, he was the senior son of Alexei and could not be ignored. Thus, when his older brother Feodor III died in 1682 and his stepmother tried to enthrone her son Peter as Tsar, the Muscovites and the Streltsy regiments rioted and forced Ivan's coronation as senior co-Tsar, under the regency of his (in)famous sister Tsarevna Sophia Alekseyevna. Ivan remained the senior Tsar but after Sophia's regency ended in 1689, he was reduced to a non-entity and played no role in the Russian Court until his death in 1696. Yet he did differ from Carlos II in one respect; he fathered five daughters, three of whom survived infancy and one of whom, Anna, became Tsarina in 1730.
So my question is this; what if Ivan had fathered a healthy son? Ivan was the senior Tsar and senior male heir, so would Peter be able to legally side-line his nephew without causing more riots and potential rebellions? How would a continuing ro-regency play out? Would we see a potential civil war as those unsatisfied with Peter's reforms gather around his nephew? Or would Ivan VI become an ally and surrogate son to his uncle (after all, Ivan's would-be mother Praskovia Saltykova was much admired by her brother-in-law, supported his westernization policies and educated most of the female Romanovs of the next generation) Any chance this nephew (Ivan VI for ease) would simply have an accident like other inconvenient male heirs (Ivan the Terrible's son Dmitri comes to mind here)? Would love to here people's views on this one!