Steps for filing amended return for IRA recharacterization that was done after filing tax return.

I contributed $5500 to Traditional IRA in Jan 2017 and converted $8500 from Traditional IRA to Roth IRA in March 2017. In January of 2018 I contributed another $5500 to Traditional IRA and convered to Roth IRA. In April of 2018 I filed my taxes on time and filed in all that. 

Fast forward few months and had significant loss in Roth IRA. I know I cant recharacterize my 2018 conversion but I can recharacterize my 2017 conversion back to Traditional IRA. When I put in all this info in Turbo Tax it tells me I need to amend my 2017 returns - which makes sense since I did recharacterization after filing my 2017 tax return. From my broker I got 2 1099-R - one for 2018 conversion and another one from recharacterization with distribution code "R".

My question is how do I go about this amended return. If I open turbo tax for 2017 and try to file my amended return for that - what do I actually amend. Do I have to file the whole return again or I only amend the IRA document and send that in to the IRS. What would be the steps for doing this - Do I delete 1099-R in my 2017 return that shows $8500 conversion and enter new one that I just received or need to take some other steps.

Thanks a lot for help