Not dynamic patching, but you can use [canvasargs] from iemguts. Updating the arguments doesn't happen immediately, but takes effect if the patch is saved and reloaded.

Barring this, I can't think of anything other than the dreaded option of sending individual mouse and keyboard messages to the canvas.

From: Pd-list <pd-list-bounces@lists.iem.at> on behalf of Alexandre Torres Porres <porres@gmail.com>
Sent: 03 March 2018 03:01
To: Pd-List
Subject: [PD] how to change an object's argument via dynamic patching

Hi, is there a way to change the argument of just one object via dynamic patching without having to clear all of the patch's or subpatch's object and restart from scratch?

It's not that I'm lazy to clean and restart, I just can't do it, for technical reasons I don't think it's important to discuss right now.

This in Pd Vanilla, of course

cheers