Incentivizing secondary attacks House Rule

[Mathulhu]

I have had an idea, now someone else just needs to make it make sense.

First A makes an attack with X and B succeeds with defence Y.
Now without making another action A sacrifices their ability to attack with X in order to penalised B's defence with Y.

Should B be able to lower their further Defence of Y to penalise A's attack with X?

I think this would help model a lot of things we see in cinema, blade-locks and sudden kicks or grabs.

Would retroactive deceptive attack, -2 to to further attack for a -1 to further defences, work in this example?