How to retroactively set a baseline in Microsoft Project

Hello - 

I've created a master program schedule that comprises of 50~ projects at a high level.
I've entered them into the baseline start and baseline end columns with start and end date columns also in the schedule.

Is there a way i can specify that the baseline is based off the baseline start and baseline end columns?

The solution I have is that I copy the baseline columns into the actuals > set baseline > change actuals columns back to what my actuals are. If i go with this solution, when i add new projects to the schedule and i add in their baseline, can i choose to update only those activities into the original baseline?

Hope that makes sense.

Cheers!