If a client runs "SMSLS.bat" or "SMSMAN" and connects to a different Sites Logon Points, the entry for that other site will show up in the "Sites" tab. However, unless the client is indeed within the other sites boundaries it won't actually report to that site. Other than the original DDR it created and sent.

For example, if you are physically and logically in "SiteA" (a member of), and you happen to log on and authenticate to a Domain Controller that happens to be located in and part of "SiteB", or run "SMSLS.BAT" in that domain, or run "SMSMAN" and so connect to the other domains Logon Point, your client will be assigned to that site and "SiteB" will show in your systems "assigned" site information.

Since running SMSMAN in automatic mode will just browse for a Logon Point, it can find any LP in any domain theoretically.

The "Principle" site (the site at the top of the list in the SMS Control Panel applet), simply has precedence over the client for configuration options, such as hardware inventory frequency etc. If the client is assigned to both sites, it will check both sites CAPs for adverts and updated configuration.

This may explain why some users (especially mobile laptop users), can get terrible network logon response times and other post-logon difficulties if they are members of multiple sites as the client needs to poll a CAP across a long and/or slow WAN link.