Mistworld — Nina M. Osier

She thought her three sons were dead, killed in battle under her command. But thanks to a planet called Mistworld, retired Fleet Admiral Catherine Romanova has them back-years after she forged an unlikely peace with the mysterious beings who caused their deaths. Now the legendary Matushka and her part-Morthan husband, forced into exile by the brutal Terran occupation of her native Narsai, must unlock Mistworld's secrets if they're to have any hope of seeing home again. Or the thirteen-year-old daughter they've been tricked into leaving behind, by relatives who believe that Catherine's heir holds the key to Narsai's freedom.