In my research for my current aar, I found something interesting in relation to this. Now, Harald Hardrada, after escaping his term in Roman service, passed through Kiev and married his "great love" Ellisiv, daughter of Yaroslavl the Wise. Thats confirmed in all the records and sagas. She produced the two daughters you see in-game in 1066. The sagas then go on to say that upon gaining the crown of Norway, he married Tora Torbergsdatter as a political sop to the nobles; by her are born Olav and Magnus. No death of Ellisiv is mentioned, in fact she is recorded in the Heimskringla as accompanying Harald as far as Orkney on the way to invade England. No big deal is made of this by the contemporaries, despite Harald, both wives, and the kingdom already being 'Christian.' To be noted, thought, is that only Ellisiv, the first wife, was Queen, Tora was only a wife. So perhaps even early Christian Scandinavian and Russian princes should have some sort of limited polygamy.