I've too recently came up with an idea for seeds and I hope some experienced cryptographers here will tell me if it's good or not.

First, we generate seed A which is our secret seed and used to create main wallet.

Then we generate seed B, which will act as a decoy.

Then we calculate a key such as (key + seed B) mod 2048 = seed A

Seed B is used to store small portion of BTC savings, so in case someone will get access to your private storage (thieves, kidnappers or police), they will get only a small portion of your coins, while you will be able to later restore your main wallet with a backup copy of seed B and the key.

My question is, is this scheme viable, or are there better ways to do it, like having independent decoy while hiding the main wallet through other means?