It's all about them.
There is help here if you'll have it, listen to it, and act on it. Read the sticky's above, and more than anything take YOURSELF to an Alanon meeting. Your posts are all about him, his family, his mother,his sister, and none of them are about you, how you got yourself into two screwed up relationships in a row, and how your life is today (and make no mistake, as wonderful as Scott may be he came with all this baggage that you gladly signed up for).
I'm going to give you some advice you can ignore or take:
1. Go to at least six different Alanon meetings, some different, before deciding if it is for you.
2. When you read posts here do not respond to them right away. In fact, read them twice, then log off and think about what you read for 30 minutes or more. Then, if you are compelled to respond, please do so.
3. Focus on yourself and your part in the dynamics you described in this post, and focus on what is and is not your business in that context.
4. Let Scott, who is an adult, manage his own damned relationship with his family. He's not a child, and you're not his mother. Stop mothering him for God's sake!
You do a lot of talking for Scott, and even included him in your name here, but I don't hear his voice in these posts. I hear yours. The fact that he doesn't have his own account here, or that you don't have your own account here (unless this is really just your account), is problematic.
Here:
How to find a meeting in the US/Canada/Puerto Rico
Take what you want and leave the rest,
Cyranoak