Dump a wallet with only a surveillance-only address.

I have two wallets consisting solely of surveillance-only addresses that I added to my Bitcoin nodes. importaddress with the passage of time. Now I want to merge these two wallets into one.

My initial thoughts were dumpwallet and importwalletHowever, the file created as follows: dumpwallet Watch-only addresses are not included.

How do I merge two wallets into one and keep all address labels?