My father-in-law is 85 and is soon to undergo tests for dementia and Alzheimer’s.
He is currently hospitalized; severely depressed from the recent passing of his wife.

He recently sold his house and his car so that he could move into an assisted living
Facility. He put the proceeds into a separate account from his checking account.

We were able to get my father-in-law to agree to put my brother-in-law on his
Checking account in order to pay my father-in-law’s ongoing bills at the assisted care facility.
My brother-in-law does not have signing ability on the second account which holds
The proceeds from the sale of the house. (The issue just didn't come up.)

If my father-in-law declines in health and requires money from the account that holds the
Proceeds from the sale of the house, no one else can access it but my father-in-law.

My father-in-law’s remaining assets are stocks, annuities, RRIF’s, and
Retirement that he depends on for income. He doesn’t own any real property (house, car, boat, etc.)

1) Should my brother-in-law try to get Power of Attorney for him? Or

2) Does he simply need signing authority on the second account?

3) If he is put on the second account, is there a tax implication if my father-in-law should pass?

This is in British Columbia, Canada

He merely needs to be added to the second account, someone may wish to be appointed guardian if he is not able to handle his own business affairs. Power of Attorney merely gives signing rights for all matters.