If a family member passes with a will, then that will determines who has the first right to manage the estate. Most wills name an executor (or multiple executors and alternate executors) to take on that role.
In Saskatchewan, depending on the type of property the deceased owned, a court application may be necessary. If the deceased owned land, bank accounts, or investments that do not automatically pass to another person or a named beneficiary, someone will likely need to apply to the Court for letters probate or letters of administration with will attached. These are court-issued grants that confirm to banks, land registries, and other third parties that you have legal authority to act on behalf of the estate.