~snip~
Alice (owner) will just set an option of N days in a wallet. Then the wallet creates transactions automatically when sees new UTXO under control. Then it will send it to heir via some standard peer to peer channel (email, messenger, etc.) From Bob's (heir) side a wallet will get and store the tx.
Yeah I got this part.
It can be new wallet software with this functionality or an add-on to existing one.
As far as I know there are no existing wallet that supports to set an option of N days so, I am asking do you have a script or are you working in it to make it easier for the regular user?