You don't say what type of dog she is.
Guarding breeds are extremely territorial, and will protect their space and owners. However, when barking becomes excessive it is a problem.
I would strongly recommend that you take both your dogs training, since this will help to socialise them with both strangers and other dogs.
If you are going to start using water bottles and rattle bottles, it should be done under professional instruction, since you can do more harm than good. Hope this helps
