Merge blog applications

There is no blog merger included out-of-the-box. We have  IApplicationMerger (v2) Plugin Type and  ISecuredApplicationMerger (v2) Plugin Type extensible plugin types if you need a custom solution.

Thanks Steven!

Few things I will add here.

You can MOVE blogs, but they would still be their own blog (picking up a container of water and moving it from one house to another, same container, in a new house), just in the target group:

You can MOVE individual posts, which will essentially merge them into the target blog:

This idea was posted and is one we are reviewing in our upcoming internal session:  Merge blogs (actually any app) 

Noted in that idea is a link to this thread:  Moving contents programmatically which is related to what Steven has mentioned.