Provided you have not already filed, you can start a new tax file.
You cannot file twice in the same year.
If you have already filed, I suggest visit a tax professional to adjust any errors.
Foreign pensions should be reported under foreign income, regardless of which currency they are received in. If pre-converted to CAD, report currency rate as 1.0000
Only report income in a T4A page if you have explicitly received a T4A slip.
There is no requirement to explain or notify to CRA that slips are not generally available for foreign pensions. If CRA wants to verify amounts, they will ask you for evidence. You could use payment amounts into your bank account, or any documentation received.
