as there is a way to save a flight at any point in FSX, is there a way of saving the PRO ATX plan at any point to accompany the flight ?

thanks

You can save a flight in FSX, just press the ; key (semicolon).

In PRO-ATCX bring up the menu with ctrl - 0, option 5 - Other Options choose Save Flight Situation. You don't (usually) need to save in FSX as that option does it for you.

When you want to resume start FSX then in PRO-ATCX right click your flight plan and select Saved Flight Situations.

Some aircraft are fine with resuming saved flights, others not so much.