>We are using multiple size stationeries for the printing. So, it is very difficult to change the paper size of the printer
Why would this be "very difficult"? If you are printing on a certain stationary that is 4" (4 inches) high, send the commands to change the page size, then immediately print the reports. The command for the page size should be part of the program that produces the report.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)