How to change the size of bars of a whole chord sequence?

[pdxdjazz]

There is no automatic shortcut to reduce the size of all the measures on an existing single page iRp chart.

To retain the original chart, be sure to edit a "duplicate".
You could use your copy/paste method to make half of the chart into a new "page 2” chart.
Then add empty systems (lines) in which you could add text.

The iRp player will only play a single page, then must reload to play page 2.

To compact a chart with 4-space measures into a 2-space per measure format requires deleting the "extra" spaces one by one.
)BOB