Multi Check In will check in all files currently checked out, this includes all files in a project group. Options for both MS SourceSafe add-ins are controlled in MS SourceSafe Options.
Checking in Your Work
Note: Multi Check In can only check in files that are part of the corresponding project in Microsoft« Visual SourceSafeÖ. For example, if you are sharing a file across multiple projects that file will not be checked in.