If there was a threat on life, you would naturally save them in that order. However there are many stories of people sacrificing themselves to save a family member or pet. I understand where you're coming from - but I don't view it as a sacrifice to save a family member.
The most important people to me are my wife, daughter, brother, mother-in-law, and brother-in-law. I'd donate an organ or take a bullet if it meant saving them - and I wouldn't view it as a sacrifice - because they are my highest values and I wouldn't want to see them suffer, and I couldn't imagine life without them.
A "sacrifice" means placing something you value much lower, ahead of something you value much higher. That is why I oppose the general politics of need.
On a funny note, I always view it as funny when sports announcers talk about players "sacrificing" themselves for their team team - I'll tell you what's a real sacrifice - giving yourself up for the OTHER team to win. <s>