@DonGiovanni It's your basic Game of Thrones shit, isn't it? Her son is third in line, she's second wife. She'd probably like Yulian and Pere dead so Orka is the next Glow, and wouldn't mind Pere's mom being dead so she's out of the way too. Hell, maybe take out the current Glow so she maybe becomes your basic "steward" type of deal until Orka's old enough or at the least, she'd be his most trusted adviser.
This is why polygamy isn't a great idea to drag into political situations, like ruling families. Each spouse increases the odds of jealous, traitorous hos. Which is a term I'll use here for men too, since one female multiple males sort of deals aren't exactly unheard of either.