Sounds like things are going great. I wouldn't worry about Haggis being bigger than Rosie - when I got Mosi, Jaffa was obviously a lot bigger than him but I just let them roll around the floor together and Jaffa would sit on Mosi but he never came close to hurting him. I'm sure Rosie can stand up for herself, esp once she's settled in! Once they are best buddies you'd better watch out - double trouble!