Any blog can have extended posts. In fact, if blog B has one then blogAll (actually blog #1) will have one because everything in any blog shows up in blog #1. To make an extended post click !M at the point in your post where you want the "read more" link to show up. The visitor will have to click through to read the rest of the post.

Thanks for that. I've tried it and it works! Is there any way BlogAll can be set to only show extended posts, say the first 500 characters of other blog postings?