Need User Input on Splitting Bitcoin SV from Electron Cash wallet

I still have not split Bitcoin SV from my Electron Cash wallet.

Bitcoin SV’s website gives instructions on how to split Bitcoin SV from the Electron Cash wallet:

https://bitcoinsv.io/coin-splitting-guides-for-bitcoin-sv/

If I follow their instructions, will I risk losing any of my Bitcoin Cash?

In fact, I haven't split Bitcoin Gold yet, from my Electrum wallet in 2017. (I sent all of my Bitcoin out of my Electrum wallet to an exchange to trade it for Electron Cash.) After I’ve split the coins into 3 coins (Bitcoin Gold, Bitcoin SV and Bitcoin Cash), do I need to be burdened with 3 wallets? Is there a wallet that is secure, reputable, can store all 3 coins offline (like the way Electrum did) and let me keep the private keys and seeds?