differencing a flag by adding something to it, such as a charge, badge, or writing. Used especially on colonial flags. Note that this term does not have the usual meaning of "vandalizing" when used in vexillology.

Defacing (which is NOT vandalizing) is when a flag is altered by adding writing, another emblem, and so on.

Changing a flag by adding something to it, especially concerning colonial flags. Note: that the term 'defacing' doesn't mean 'vandalizing' when used in reference to flags.