L want to gather all wallets belong diffrent browser extension to one browser extension

Hello my friends,

l use my metamask wallets in 3 different browser extension because each have their own different seed(secret recovery phrase) words. But l wanted to gathert 3 wallets. So l looked a title “How to import an account” named on metamask support web page.

in first paragraph of this page is writing that: “NOTE: Imported accounts ARE NOT BACKED UP by your Secret Recovery Phrase. Even though they will appear in your MetaMask wallet, you need to save the private keys used to import them the same way you save your Secret Recovery Phrase. If you delete your wallet and need to restore from your Secret Recovery Phrase, you will need to re-add imported accounts with their Private Keys.”

So l thought this: " l wonder if l import other wallets into one browser extension with private key and then if l lose this wallets somehow, Will I ever be able to save wallets l added with my seed words? Or else will l able to use with only private key so as to recovery the wallets?
Clearly l wonder if l will be able to use my secret recovery phrase always, even if l imported that wallet before. What do you think about this?

Thank you to read