How to implement Bumpless Transfer on PID controller on simulink?

I developed a simple PID controller on simlink that lets me choose between "auto" and "manual" operations.

And the subsytem:

On auto mode, the output of the controller is the calculation of the PID algorithm on the error (SP - PV) and when in "manual", the operator is able to force a desired signal in the output of the controller. It works but I found out that "Bumpless transfer" is a thing and I decided to implement this function on my controller. The result I'm looking for is: whenever I switch from "manual" to "auto" the output of the controller should be the same. I've tried to use the basic PID block from simulink with the tracking mode function but for some reason it seems like it does not work properly, so I'm trying to do this manually.

I don't know how I could do it on simulink. Something important to point out is that i'm generating C++ code and implementing this controller on a arduino hardware, so I'm able to use normal arduino code and manipulate the signals coming in and out of the subsystem also, and the truth is that I've been trying to solve this issue this way, but with no success. Does anyone here know a thing or two about Bumpless transfer on Simulink/Arduino?