One who tacks riders on bills

• Change maker
• One proposing a rider to a bill
• Maker of a change or revision
• One changing a bill
• Constitution tweaker
• Revisionist
• Person who makes change
• Copyreader, e.g.
• Unexpectedly named by Queen, one changing for the better?

Wiktionary Word definitions in Wiktionary
n. One who amends.