A Members page is related to a BSCW Group (see section 4.5.3). You create a BSCW Group and its Members page when you turn a Folder, a Meeting or a Discussion into a shared Workspace (see section 4.4 and section 6.2.1).
The Members page will "disappear" when you remove all members except yourself, i. e. as soon as the object is no longer shared.
You create a Participants page when you create a Meeting (see section 5.1 and section 6.2.2).
The Participants page will "disappear" when you remove all Participants except the BSCW Group 'Members of the Workspace that contains the Meeting'