Great posts here for a worthy cause. I have been "adopting" (rescuing) dogs and cats for over a decade in the US and brought my adopted dog and cat with me when I moved here 6 years ago. i strongly agree about the importance of puppy kindergarten classes also. I also had adopted an elderly chihuahua (9 years old when I got her) and she went on to be a great companion fr 5 more years!
One thing not addressed here is beepokerking's concern about potential size..for me its always been an issue since I travel and want to be able to take my dog with me UNDER THE SEAT of the plane. And the height current requirements are very limited--8 inches height more or less at the shoulder. For this reason I have stuck with purebred toy or terrier breeds--and at least in the US, there are breed specific rescue groups. (They specialized in rescuing, fostering ad adopting their breed from the recently deceased or no longer able to care for their pets.) Beepokerking, perhaps ask a vet here about that..Obviously to adopt a full grown dog within your size limitations would be ideal. But puppies are adorable and sometimes better integrated into an existing family. You can pretty realistically predict adult size of a mixed breed puppy by knowing the size or breed mix of the parents, looking at the puppy paw size, or if you're really knowledgable about breeds, diagnosing the breed mix yourself. I'd be willing to help you with that and "puppy character test",if you don't currently have knowledgeable friends to help you, for free of course! Wish I could add another one myself but the airlines only allow me one! Best of luck and keep us posted if you adopt...And Frenche," te felicito" on your extended family!