Defensive Playbooks and Custom Plays

I'm new to this series, and wondering if you guys can help me out.
1. How do I set up blitz plays in a custom playbook? When I create a playbook, there are no blitzes listed among the default set of plays. I've noticed that Plays.xml has a set of blitzes in it, but these plays aren't available in the game. How exactly does the "blitz ratio" on the strategy screen for defensive playbooks work? Ultimately I'd really like to prioritize blitzing certain players in my gameplan (e.g. Sam LB blitzes), but this doesn't seem to be possible right now.
2. There appears to be a few problems with custom defensive plays. First, the graphic does not illustrate player actions for defensive plays:

Second, editing custom defensive plays doesn't appear to work properly; when the screen comes up it appears to believe that it's an empty offensive play rather than a defensive one.
Finally, is there a way to delete custom plays? You can "delete" them from a playbook, but this just puts it back into the list of all the other play. I'd like for a way to fully delete the custom play, or at least to rename it.
1. How do I set up blitz plays in a custom playbook? When I create a playbook, there are no blitzes listed among the default set of plays. I've noticed that Plays.xml has a set of blitzes in it, but these plays aren't available in the game. How exactly does the "blitz ratio" on the strategy screen for defensive playbooks work? Ultimately I'd really like to prioritize blitzing certain players in my gameplan (e.g. Sam LB blitzes), but this doesn't seem to be possible right now.
2. There appears to be a few problems with custom defensive plays. First, the graphic does not illustrate player actions for defensive plays:

Second, editing custom defensive plays doesn't appear to work properly; when the screen comes up it appears to believe that it's an empty offensive play rather than a defensive one.
Finally, is there a way to delete custom plays? You can "delete" them from a playbook, but this just puts it back into the list of all the other play. I'd like for a way to fully delete the custom play, or at least to rename it.