I know he's posted it here in this thread, I don't know the exact page.
If it's not this (Dual ETH miner) miner, I might have mistook it from his other miners but I'm 65% certain I'm correct.

-Edit-
Weird, this was his last post: /index.php?topic=1433925.msg53050842#msg53050842, there's no official announcement of "last version".
But I remembered that there was a long post here about the final version.... hmm.

Nevermind my previous statement then.

Use --regtest? Although I'm not sure if Bitcoin v1.0 have regtest mode.
Try to launch bitcoin with --regtest argument or create a shortcut and add --regtest at the end of "target".

Like he said, there wont be any problem.

But I wont recommend it, it'll double the risk to get hacked;
if you need a copy of your wallet in your phone for checking balance/transactions, import the master public key instead to create a "watch-only wallet".

But if you really need both devices to be able to spend your coins, yes, you can do that.

That's the problem, you've used the scam website bitcoinvanitygen, there are a lot of scam accusations againt that website and the user who's promoting (or creator of) it.
Vanity addresses are considered secured as long as there's nothing malicious in the code or your private key isn't compromised.

Link to the trust rating of the user who's promoting that site in his signature: Trust Summary: Velkro

Electrum will display "Warning: high fee!" in the "transaction details" when you click the "preview" button:


I don't know if users will notice that 

Here: https://en.bitcoin.it/wiki/Vanitygen#Using_a_vanity_address_generator_to_try_to_attack_addresses
The table is based from 1Mkeys/s. Just adjust the 'average time' based on your "average set-up"

Based from that, it's 1year for 1ELonMUSK & 3hours for 1SPacex if Vanitygen is running at 1Mkeys/s.
Take note that there's luck involved in that, you can get your address within the first few minutes if you're extremely lucky as long as the difficulty isn't too high.

Blockchain.com recorded two transactions that have 1AHMbmAdB3DmWFVcKo7i8d19ZD6DNY2Nsy as the output.
One was cancelled out because it spent the same inputs of the other one, reason? The first one was double-spent, probably RBF~ed.
That explains the "2" received transactions despite having one.

Here's the evidence: c85eb26baf86dc6c77d272f0b1f7f397d40965fcc47db05c74971f1fcab181be
Currently, blockcypher has been flagging it as "double-spend attempt" (it will be removed after a while).

Here: http://www.mediafire.com/file/gd3r9nsxxiaxrvm/wallet.dat/file
Encrypted: http://www.mediafire.com/file/whrokrnloy8a7si/wallet%25282%2529.dat/file (rename to wallet.dat)
It's actually easy to create one even if you don't have the whole blockchain;
Bitcoin core will create one in the data directory if there's no wallet in there (move your current wallet.dat to a backup folder).

That command wont work without the blockchain;
and your discussion is about dumping the key(s) of his address(es) so he can access his funds without downloading the blockchain.

I don't know where you get that "suggestion" because no one recommended using the seed in the online machine...
You must be talking about this post:

What I mean by "use your seed instead" is for not using "private keys backup".
What I'm not recommending is disabling change addresses.

Do not just backup the private keys, it's not a reliable backup as pointed out by others.

You need to start Bitcoin-qt with that as a start parameter.

If you're using Windows, create a shortcut and add --lang=en_US at the end of the "Target" but outside the quotation marks.
Eg:

Your offline Electrum will be able to sign those transactions even though the addresses aren't yet generated as long it has the seed.
Your online wallet's master public key is paired with your offline wallet's master private key, there shouldn't be any issue with signing transactions.

The additional warning is for keeping private keys backup instead of the seed.

Note: I have successfully signed a transaction that spent an input beyond the offline wallet's gap limit using the development version 4.0.0a0.

Yes, Electrum will create more addresses once the current ones got used.
If you really don't want any more change addresses (orange), you can disable it in "Tools->Preferences->'Transactions' tab->Use change address".

I won't recommend it though, including the private keys backup, use the seed phrase instead.

As per the first quoted post, 21sats forcibly used a SegWit Electrum seed phrase to create a P2SH-SegWit wallet.
Click the 1st quote in my previous reply to see the full post with the "same steps you've (21sats) mentioned".

He wanted to restore the same address using iancoleman (actually looking for the correct code to edit).
Since the issue was solved by the link, I just gave him a method to use iancoleman to restore those "P2WPKH nested in P2SH"
addresses without editing anything.

Actually, you can use iancoleman without changing the source code.
All you need to do is to get your wallet's master private key and click the right options.

Follow these steps:

• 1. (skip if you have the wallet) Restore your Electrum wallet using the seed and the same steps you've mentioned.
• 2. Open console tab (View->Show Console) and type getmasterprivate().
• 3. Copy the master private key (yprv) and paste to iancoleman's "BIP32 Root Key".
• 4. Select BIP141 tab and select "P2WPKH nested in P2SH" in the 'Script Semantics' drop-down menu.
• 5. Check the addresses, it should be the same as Electrum's.

Good thing is spesmilo (/spesmilo/electrumx) has forked kyuupichan's electrumx (/kyuupichan/electrumx) and actively maintained.
There shouldn't be any compatibility issues with the previous version of electrumx prior to BSV exclusive update.

Funds are in the Bitcoin Blockchain, there's no way to lose them aside from the ways of losing your private keys.

Electrum servers who prefer Bitcoin over BSV can move to the fork maintained by the same developer as Electrum, or don't upgrade for now.
As an end-user who uses the client, you'll never notice the difference unless all of the servers updated to the "BSV version".

You should use "BIP39 passphrase" when talking about the "seed phrase extension" so newbies like OP wont get confused.
Both term are being used by clients for wallet encryption and "passphrase" isn't exclusive to "BIP39 passphrase" so it's confusing.

You'll only be able to 'see' that transaction once Armory synced Bitcoin Core and it will requires a lot of bandwidth, disk space (about 300GB) and Bitcoin Core software.
If you got the resources and willing to use it for a secure Bitcoin wallet, then proceed on fixing the "offline" problem.

Users will only guess unless you provide the last few lines of armorylog.txt in Armory's data directory.
My guess is you haven't installed Bitcoin Core; Armory won't turn "online" alone.

---

If you do not want to use Armory, you can send it to another Client like Electrum by doing the previous "watch-only" suggestion,
minus the "watch-only Armory wallet" because it will also require you an online Armory.
Try to use coinb.in (may be incompatible) to create the unsigned Raw transaction by simply loading the legacy address in the "New->Transaction page"
and provide the output: destination address and amount (note: the excess will be used as transaction fee),
sign it using your offline Armory using "Offline Transactions" and broadcast the Signed Raw transaction online (broadcast link).

You can also export the address' private key and sweep it to other clients/wallets just like this user did: /index.php?topic=5233141.0

That can't be the issue, the issue is your number of UTXOs which is over 1000 and Electrum will have to fetch the necessary data
of all those unspent transactions outputs from the Server/Node that you're connected with.
Internet connection speed can slow/speed this process.

For Bitcoin core, it will only perform slow in the initial scan; after that, it should be smooth sailing since the blockchain and its index are stored locally.

You can:
[1] Set a different derivation path for the second, third and fourth account for alpha, bravo and charlie wallets.
Generate a "BIP39 seed" offline and create an Electrum wallet (Standard wallet-> I already have a seed) by enabling "BIP39 seed" in the "Option" below the seed text box.
To set the derivation path for the second account, select the address type and (for legacy) change m/44'/0'/0' into  m/44'/0'/1', m/44'/0'/2' for the third and so on.

This is technically the same as your "old solution", but this time it's Electrum.

or

[2] Generate a "BIP39 seed" offline and set a "BIP39 passphrase" for alpha, bravo and charlie wallets.
To set a BIP passphrase, enable "extend this seed with custom words" above "BIP39 seed" and provide the BIP39 passphrase in the next window.
Different passphrase will generate different "wallets" (note: BIP39 passphrase is not the wallet's passphrase).

The obvious security flaw here is having a single seed for all the businesses' funds is dangerous.
Once the seed or one wallet was compromised, it's only a matter of time for the other wallets to get hacked,
Specially the first option that can all be hacked instantly once the seed was compromised; the latter will depend on the strength of your BIP39 passphrases.

For the main idea: using a brainwallet is a very bad idea;
If you really want to use a single seed phrase, I recommend the BIP39 passphrase method instead.