I have a new client who has excess Roth contributions for 2016  to the present.  I need to file Form 5329 for 2016, 2017, and 2018.  The client previously filed those returns on time.  Do I need to file Form 1040X and attach the 5329 Form to each of those years?  Or can I correctly file Form 5329 as stand-alones?  The IRS instructions are confusing.