The law came in to increase the trespass

The law is not a remedy for sin. It does not cure sin but rather makes it worse. St. Paul says it was given to make sin apparent, indeed, even to increase it. It doesn't do that necessarily by increasing immortality, although that can happen when rebellion or the power of suggestion leads us to do just what the law is against. But what the theologian of the cross sees clearly from the start,is that, more perversely, the law multiplies sin precisely through our morality, our misuse of the law and our success at it. It becomes a defence against the gift.

(italics original (bold by me), p.27, Gerhard O. Forde, On Being a Theologian of the Cross: Reflections on Luther's Heidelberg Disputation, 1518)

So the law does not increase sin by making us more like younger brothers, but like older brothers which is worse.

I can't believe that this thought is new to me. It is one of those occasions where I wonder whether after all my reading I'm still yet to really get Luther's main points.

But does it make sense of Romans 7 to see sin increased by:

(a) increasing immortality; or

(b) through our morality as a defence against the gift?

I'm not sure. But I think the fact that it is the sin's deceit that Paul draws attention to (v.7) may support Luther and Forde.