This sounds like our meetings... we usually tell any guests with announcements to come early and we let them do it just before the meeting, or come to a non-formal meeting. But as far as new members we do exactly the same thing.

Actually only our CBM's are closed since we do ritual, but we can have guests at our regular meetings if they are invited.

Yeah, CBM is closed. With regular chapter, I think it just varies from chapter to chapter as to whether or not you want others to be able to come. I know it's allowed and we (on occasion) have had guests (i.e. Greek Life advisors, speakers). But in general, we keep it to new members, actives, and alumnae. :)