Remember, for example if you split your seed phase and store it this way A-B-C-D-E-F (location 1), D-E-F-G-H-I (location 2), G-H-I-J-K-L (location 3), J-K-L-A-B-C (location 4), this has a 1/4 fault tolerance, so if somehow you can't access one of the locations you are still safe, but if you can't access 2 locations from 4, you already have a problem as your seed is gone.

With the proposed solution what you will need:
1. a non custodial wallet where you will hold all your bitcoins (wallet A to be backed up)
2. a custodial wallet where you do the KYC but not hold anything there (this can also be another non custodial wallet) (wallet B where we send your coins if you need to activate backup)
3. an account with us that you will use in case you lose your access to your non custodial wallet (wallet A)

So, basically all your funds will stay forever on the non-custodial wallet but you will need wallet B only if somehow you lose the private key / seed phrase of wallet A. In this case, all you have to do is to login to the backup service and use the previously signed raw transaction (you signed it when you could still access your keys) to send all your funds to your wallet B. Since, wallet B is a custodial service (which is an advantage in this case), for example Coinbase, Bitstamp, etc., you simply login back to this service and voila, you have your bitcoin on the wallet B. If, for some reason, you forget the login and password for your wallet B, with proper KYC proof, they will let you in, and your funds will be safe. Of course, after this is done, you simply withdraw your funds from wallet B to a new wallet you are creating just to not keep your coins on an exchange.