step7: note down the seed and passpharese.
Note them down at least twice each on at least 4 separate pieces of paper. Noting them down together renders the passphrase pointless, as if someone compromises one of the two pieces of information then they have compromised them both. Noting each of them down only once gives you no redundancy and leaves you open to risk of total loss. Store all 4 pieces of paper separately.
note : i would have used talis and electrum but i want to make a bip39.
You can still use Tails, and instead use /dev/urandom to generate your entropy and import that in to Ian Coleman to get around the issues discussed above of generating entropy in a browser.
OP, why not use Shamir's secret sharing? I think Ian Coleman has mnemonic tool for that, and it would allow for a better setup than this.
Because
https://en.bitcoin.it/wiki/Shamir_Secret_Snakeoil. If you want some sort of m-of-n system, then a better option is to use multi-sig.