Condolences to you and your family.

Process in today's world, real life and online life.
Get access to as much of the following
1. Emails, personal and business (es).

This might tell you all subscriptions, loyalty memberships (airline, hotel, etc), employer if worker/customers if a business, LinkedIn, FB, messengers, SMS, banking, etc
2. Employer / Colleagues

3. Subscriptions ...website domain ownership providers, newsletters, etc

4. Loyalty Memberships (airline, hotel, etc)

5. Banking (credit cards, accounts, etc)

6. Insurance policies ...car, home, medical, life

7. Twitter / Linkedin / FB / IG etc

8. SMS and Messenger Apps (FB, WhatsApp, Viber, Telegram, etc)

Most websites/apps/loyalty programs consider(ed) only their users as being alive. Gmail has a nice way of Inactive User after __ months, contact ___. FB put smth also.

For sibling who died...started in email looking for key items, but also cancelling "clutter" (newsletters not for money, notifications from postings in social media/etc) to better "see" the important items.

Again, condolences.