Platform terms of service forbid it (accounts are personal and non-transferable), and a platform may block the account when it detects the login. In practice families do this; a safer and more durable route, however, is through official mechanisms, especially for accounts of great sentimental value.
Put your most important documents in one secure place
Sejf Życia is an encrypted space for documents, access details and instructions for loved ones. Only you decide who gets access, and when.