It is required that the deceased spousal return is done separately. In the past they have always been done jointly. By doing them separately, there is no prompt to allow the split pension income amount. On the alive spousal return, the pension income was allocated to the spouse. The T1032 form is filled for both spouses but it seems to require an "override" to complete. Not only for the split pension amount received but also for the calculation in the box "Marital Status Change" on page 2 of the T1032 form. The deceased was still "married" on the date of death.
Sorry for your loss. Pension splitting can be performed in the year of death, however, it is a pro-rated calculation based upon the date of death. In your case, nine months apply and this should be able to be completed without performing any overrides using TurboTax Online or Download/Installed in your computer.
I'm going to suggest contacting our Customer Support team for assistance with this. Here's how to contact them:
https://turbotax.community.intuit.ca/replies/3152013