The simple explanation of the worry about point loads is
If you want to break a stick you might put you foot in the middle and pull up one end and if it doesn't break it will bend at the point where you have your foot.
You are not talking about a lot of weight as each sheet of drywall is either 50 or 70 pounds and you can figure what that might total for the ceiling and you will be holding half of the total.
Just cut some blocks to match the height of the floor joists and put them between the beam and the sub floor plywood so the weight is transferred directly to the beam.
While you are there check the nailing on the beam, there should be 3 nails every 16 inches on both sides.
The over kill would be to add another 2x10 to one side of the beam in the sections in question..
That said back upstairs, I understand you want three posts, for the same money I would do the structure for two even if you add the third.
Set 2 2x12s near the wall, build the two temp walls to hold the ceiling up remove the wall.
Use a chalk line and place to lines on the ceiling joists 3 1/4 inches apart and cut the that out .
Slide hangers onto the ends of every ceiling joist then nail the 2x12s together with 4 nails every 16" and slide that up into place, set your end posts and go upstairs and nail the hangers then remove the temp walls.
It's all easy from where I am sitting
Keep in mind that the ceiling joist also hold the outside walls from spreading, so if your 3 1/4" grows a little we would get a little excited about that.