I have a twitter account that I used solely for travel posts that I want to import into my existing micro.blog. In reading the importing tweets help page, it sounds like that will simply create a second blog with tweets as posts. Is there a way to incorporate these directly into my main blog, or do I need to create this secondary site, then export, then import that export into the main blog, then delete that secondary blog?
Just wondering if I’m missing or misunderstanding something.
Yeah, you’re right that the tweets will be hosted on a dedicated blog. But you can still include them on your main blog, like @manton has done here: https://www.manton.org/tweets/.
If you absolutely don’t want that second blog, using the export, import, and then delete approach should work as well.
I don’t recommend importing tweets directly into your blog unless you have a fairly small number of tweets, like fewer than 1000. If you have many thousands of tweets, as some people do, it tends to bog everything down and clutters the interface for finding blog posts.
We used to have direct import of tweets into your blog, and based on feedback about it, we switched to this new approach of having tweets in a separate blog but as @sod said you can “include” them in your main blog. I think this is the best approach.
Of course, it’s your blog and you can copy the tweets in if you want… 
Just keep in mind that deleting thousands of posts if you change your mind is a little tricky.
I only had ~180 tweets for that account (nearly all of them photo tweets from a few trips), so I went ahead and did the import-export-import method. I also cleaned up a few random tweet replies before the final import into my main blog.
I wasn’t clear on which format to export and how to import. I ended up exporting in WordPress WXR format (.xml) and then importing via Wordpress. It might be helpful to mention the preferred export type for micro.blog specifically, and then add micro.blog as the “import from” method to make it more clear how to merge existing micro.blogs. Anyway, the WXR to WP method seemed to work for this use case, as far as I’ve seen thus far at least.
Also, one other suggestion is to allow a user to select a category for an import.