Koga's younger sister Aya showed up a couple times in the anime, which would make her Janine's aunt. I don't believe she showed up in the games or the manga at all, so she might just be an anime exclusive character.
As for Janine's mother, she may very well be a ninja herself that stays out of the spotlight, but either way, I don't expect we'll ever get the chance to meet her. Just like your own mom in the Hoenn games, I don't think random trainers care too much about her, even if your dad happens to be a Gym Leader too.