Well, there is a method that you can use which is similar to that of introducing a new dog into your home.
This method is especially good for dogs with behaviour problems, PTSD, or anxiety and stress related issues.
- You should first introduce the dogs to one another on neutral ground. This could be done at a park close to your home or at the end of your street.
- After they have become acquainted, you can then walk them to a more restricted area of your home like the back yard. It is important not to restrict them to the house yet as they will feel stressed if they don't have a means of "escape" in case either one needs it.
- Allow them some safe play time and let them get to know one another. Remember sniffing is okay and it's their "hello", so let them have at it.
- Once you sense that they feel comfortable together, you can perform a couple of basic commands with them individually and then together such as sit and stay. This will allow you to be able to control them if the need arises. If one dog is generally "superior" to the other, you will know it right away. You can acknowlege their status by giving them treats accordingly.
- If you are comfortable with their demeanor and they are responsive to your direction, you can then allow them into the house.