Create watch-only wallet in Electrum from command line.

I'm trying to receive notifications for a multisig address from command line in Electrum wallet.

AFAICT there are 2 ways of receiving address notifications with electrum as merchant server backend:

Following the merchant documentation for websockets notifications.
Using notify command would send POST requests to my server.

* I know the merchant documentation, but I don't want the addrequest command to choose one of the existing addresses, I want to specify one of my own, like a multisig one.

* I've also tried the notify command that sends a POST request to a specified URL. My server didn't receive any notifications on testnet.

So the last thing I've tried is running the addrequest command specifing a watch-only wallet for that particular multisig (with -w param.) and hoping it will generate the payment request and work as well with websockets as in the merchant docs with autogenerated addresses.

-----
It gives me the following error while trying to create a watch only wallet (restoring from address):

Code:

electrum -w walletfile.dat --testnet restore mtestnetbtcaddress

If wallet file doesn't exists, the above command would return:

Code:

Error: Seed or key not recognized

If wallet file does exist:

Code:

Error: Remove the existing wallet first!

So:

- merchant docs seems to work only for autogenerated addresses.
- notify command for adding multisig addrs does not send post at least on testnet.
- I couldn't create a watch-only from restore command.

thanks in advance.