Safe to change OS and apply 3bar at same time?

[1992-25th]

I am in the process of building a base tune for my new project and have a quick question.

I am switching from my stock OS to a 12212156 OS in my silverado. I know I have to do a write entire for the change to take effect. I am also going to be applying a 3 bar OS.

Am I ok to apply the 3bar to the 12212156 OS and write entire to my truck all at the same time? or should I write entire the 12212156 OS THEN write entire again to apply the 3 bar OS?

[schpenxel]

Gen 3 or gen 4? I can move the thread there if you don't get any replies here.

[Montecarlodrag]

Since a write entire always overwrites what the pcm currently has, you can make all the changes at once then write entire.
After that, write calibration only for all changes.

[1992-25th]

Thanks for the reply, it is a gen 3