Many regulatory frameworks require that one shows proof of the source of funds - so to use cryptocurrency in the real world, it would be helpful to link outward transactions with the initial inward transaction recorded as being the "entry-point" in a user's wallet sphere.

This is already used internally for tax calculations - but it would be helpful if it can facilitate source of funds checks too, though I don't know how it would work for shared-pool regimes, but using a FIFO method to display the source of the funds used in a transaction outwards, would already be very helpful