Does anyone knows how to do a rights or things return, when you have filed final return for a deceased last year but the deceased got some more income this year from dividend and capital gains

You can only do a Rights and Things return if the dividend etc that they received were earned (that is, declared) prior to death but received after death.  If they were, instead, amounts paid to the Estate of the deceased after death, then you have to do a T3 return.  If it is a Rights and Things return, then I believe in Profile you just mark it as an "Elective deceased return" on the Info screen under Filing (right hand column), and then on the T1 itself write "Rights and Things" on the blank space at the top of page one.

Agree with Janis answer.  No rights and things.....income earned after death requires a T3 return or perhaps it may go on the beneficiary return

Janis has the right of it; a "rights or things" return generally applies (there are a couple of exceptions) to income which is owing but not received as of the date of death.  For a senior who dies before about the 25th of the month, this will mean any CPP and OAS payments, as well as any company pension.  For dividends to be eligible for this extra return, BOTH the declaration date and the date of record have to be before the taxpayer died. 

I suspect that, in this case, you will find the relevant dates are after the taxpayer died, but no one notified the issuing company so the T slip is in the taxpayers name.  Am dealing with something similar in that some mutual funds were sold early in 2021 but the executor only got the information this year so we are scrambling to do a late T3 return.

Jo Ruelle