Impact of modifying table columns on existing application, reports,business functions

Hi - We have a business need to modify an important custom table , which is used extensively in multiple applications , reports , bsvws , bsfns and NERs .

What will be the impact if we modify the table to have new columns at the end of the table ? We plan to leave the existing columns as is.

Do we need to validate event rules for all applications and reports or just test them after making the table and corresponding business view change ?

Thanks.