
Sounds like she may be younger than you think. this is typical juvenile behaviour and will improve if your boy puts his foot down, otherwise if it is only you the behaviour bothers then distraction training the only way to go, she has an active mind and needs to use it. Once you have built some kind of relationship with her and have some relevance to her then you can start to teach her to chill too.
My current youngster at 15 months often provokes and pesters the others to play. If they are not so inclined she eventually settles with a harrumph, or I will give her a hoof to chew, or have a game. This is the ideal time for you to do some training (must be a great new game in her eyes).