I guess my initial thoughts are this:
What is your definition of "Welcoming"? Do you feel like an Easter dinner is implying you are welcoming her into the family? Having her over for dinner is not the same as creating a relationship with her.
What are you afraid of will happen if she comes with your son for Easter?
Just a couple of things to think about. Remember, you can always make it clear what this invite means, and what it DOESNT mean, and that you expect sobriety at your home.
I don't think you have to "handle her". You really just need to tolerate her for a few hours. I think it would be nice for his sisters and daughter to see him if he is indeed currently sober.
JMHO