Ok. About Lithuania. In 1251 grand duke of Lithuania Mindaugas sends his negotiator/diplomat ( name: Parbus) to Rome to meet with pope and announce about dukes iniciative to baptize. Pope Innocent IV announces bull in wich he says Lithuania is his vasal (theoricaly

) . In 1251 Mindaugas and his family were baptized by livonian bishop. In 1253 July 6 Mindaugas and his wife Morta were crowned, later in 1255 pope Alexander IV allowed to crown Mindaugas son as a heir. Lithuania became kingdom. So I think it is clear enough that Mindaugas was not usurper and got crown from pope himself

.