As alluded to in your OTHER post, (T 3 Questions) It does not matter what TD Waterhouse did do or will do, or when.
Do NOT take direction from them at all.
Also, your wording indicates some confusion as to the various dispositions, distributions, or even as to who owns which assets, since you do not appear to have copies of the Estate Accounts, listing what is and is not held in the Estate, and when, and are using such terms as “main holder” when referring to accounts which may or may not be established as 50/50 JTWROS accounts…
The wife did have dispositions on DOD, so the T1 final would need to show that…
The Beneficiary is not the one who calls the shots.
Regarding the wife, you need a clear engagement from the EXECUTOR. Regarding the wife, it will be the EXECUTOR who is your client, and you need to ensure a proper Engagement letter from the EXECUTOR for that purpose.
If the Executor is the husband, and he is not of sufficient sound mind to produce instructions, if it were me I would reach out to the Estate’s lawyer.
You said that the wife died in late 2018, which means that at least one T3 deadline has ALREADY PASSED. Unless she died on exactly 31 December 2018, the first T3 deadline is not 30 March 2020.
I could make some guesses as to what likely has been happening, but since that would not be based on the actual documentation, I hesitate to speculate.
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“Since this is the first T3 I have had to complete, What is the best way I should proceed?”
… You sure you want to do this at this time?