If you don't have a multisig or social recovery wallet, imo the next best is to split up your seedphrase with a "poor man's 2-of-3": chunk 1 is top + middle, chunk 2 is middle + bottom, chunk 3 is bottom + top.

We could even use the kind of paper that people use to sign two copies of a form at the same time for this:

Followup: actually you should do this with 24-word seeds and not 12-word, so that there is enough remaining entropy to make the wallet secure even if one of the chunks gets stolen.

Would it be a good advise to fill each chunk with random words and let the recipients know that they have 1-16, 8-24, etc? Something they have and something they know? (Or maybe  “ignore the first 5 words”?)