This example may have some errors but it ought to give you an idea how to deal with these kind of problems when you have a sequence of events.
If one would like to be able to pause in the middle of the sequence just use the run flag in the actions to stop appropiate outputs and maybe in the sequence so a transition doesnt get triggered. The example operation cannot be paused even if the stop button is pushed the operation will do its cycle to the end before it stops. I have a digital input for when the tank reaches 48 degrees. In my example you have valve a and valve b one for each product both uses the same pipe and flowmeter to get down in the tank.
Made an exampleprocess with first design and then implementation.
