As @Marc_Dillon pointed out and you now realize, the workflow must run for each Member. That is the only way to get an email to each individual person.
The question is how can you get the Meeting details when cycling through the members? A template can run queries against other tables. Is there some way the template can identify which meeting invite when the PDF is being generated? If so, then you can write that query inside the template to pull those meeting details.
If not, then you must have some way to link the meeting to each person for purposes of including the meeting AND the member info together into the template.
What I would do is create a two-step process for each meeting invite added.
The first step is a custom action (or set of actions) attached to the meeting save. It adds rows to a “working” table for each member - populating the member ref along with the meeting ref. Maybe just member ref and meeting ref columns are all that is needed.
The second step is a workflow triggered on the adds to the “working” table - one for each member - to generate the PDF from template. To keep the “working” table clean, you can add a step in the workflow to delete the row once the email is sent.