This worked for me in webdriver.io

var webdriverio = require('webdriverjs-angular');
var options = {
    desiredCapabilities: {
        browserName: 'firefox'
    },
    ngRoot: 'html' // main application selector
};
 
var wd = webdriverio.remote(options).init();

var wd2 = webdriverio.remote(options);
wd2.requestHandler.sessionID=wd.requestHandler.sessionID
wd2.url('http://www.seamless.com');

This worked for me in webdriver.io

var webdriverio = require('webdriverjs-angular');
var options = {
    desiredCapabilities: {
        browserName: 'firefox'
    },
    ngRoot: 'html' // main application selector
};
 
var wd = webdriverio.remote(options).init();

var wd2 = webdriverio.remote(options);
wd2.requestHandler.sessionID=wd.requestHandler.sessionID;
wd2.url('http://www.seamless.com');