Hi Sue, thanks!
My site folders are one level up: both are in the /www/eh000/ folder. The thing is, EngineHosting states that this is how they always set up secondary domains:
/www/eh000/public_html/
/www/eh000/seconddomain_html/
/www/eh000/thirddomain_html/
So I’m inclined to stick to that, as EH prefers it that way. There’s nothing in the User Guide for the MSM that suggests any best (or only) practice for setting up secondary domains for use with MSM. Since I’m hosted at EH and following their best practice, I would think everything is set up under optimal conditions for EE and MSM.
By the way, the info in the Wiki entry I mentioned (http://expressionengine.com/wiki/Multiple_Domain_Login/) is not entirely the same as the info found in the mod.member.php file:
Multi Site Login
The login routine can set cookies for multiple domains if needed. This allows users who run separate domains for each channel to have a way to enable users to log-in once and remain logged-in across domains. In order to use this feature this array index must be added to the config file:
$conf['multi_login_sites'] = "http://www.siteone.com/|http://www.sitetwo.com";
Separate each domain with a pipe.
Here there is no mentioning of “If using MSM, you should include index.php at the end of each domain:” as is stated in the Wiki. Also, both still use “conf” instead of “config”, which as you pointed out is not correct.