Quote from: ETFbitcoin on April 15, 2020, 11:40:39 AM

You'd lose HD wallet feature, which force you to backup wallet.dat file regularly. OP apparently trying to merge multiple wallet.dat without losing any features or advantage each wallet.dat have.

He will only need to backup once after he imported the keys or dumpwallet file.
After that, the 'new backup' can still generate the new/future addresses/keys as long as the hdseed is the same.
Old backups however wont contain the imported prv keys.

Quote from: R.I.U. iol on April 14, 2020, 04:39:31 PM

I don't know if this helps, but you can:
export the private keys from both wallets

Better use dumpwallet on wallet1, then importwallet the dump file to wallet2.
That's doable within a minute if you're fast, minus the rescan.