I missed a filing T3 form (< $50), submitted my return last Sunday. Receiving refund next Monday. I am trying to add a new T3 on the website now, but fields are disabled.

[abou]

From reading online, it seems my options are "Change My Return" from CRA website or submit by mail an adjustment.
I have boxes: 21(capital gain), 26(other income) and 42(Return of Capital). In the "Change My Return", I can find only the first 2 corresponding boxes:
Capital gains:
  127-Taxable Capital Gain
  176-Information slip - Capital gains (or losses) from all your T3 slips
  254-Capital gains deduction
Other Income:
  130 - Other income.

A couple of questions:
1. After changing these lines online on CRA website, I don't need to change the calculation of the final refund balance. They will do this, right? Or I need to go from my source data all the way to the assessment end result like what turbo tax does - but manually?
2. Box 42 - return on capital is used to adjust cost when I sell the stocks, I don't need to report this to CRA, no?

Thanks a lot!

[TurboTaxMary-Ann1]

If you have already NETFILED your income tax return, you will need to file an adjustment request to make the necessary corrections.  Please use the following FAQ for instructions:

https://turbotax.community.intuit.ca/replies/2647992