I feel, if I were Isekai'd into such a position, I'd be worried about having multiple wives cause I'd hate them scheming to hurt each other or push their child as the heir or other shit :\ so if they can actually be friends and like each other, cool. But, man, Yulia (I prefer it as Yulia) is quite the cutie. Though so is Tetra. Wonder if there'll be more wives to his harem lol.