You might consider only showing one post per page in your home blog, then every time you add a new post the older one will be put in the archives or accessed by a "Next page" or "Older articles" link. That way you wouldn't have to move anything.

As to your actual question, I don't know the answer. Perhaps someone else will.

I don't realy see the advantage of your system.
I can see why you do it, but I don't agree with the way you do it.

If you post something in the desired blog, you can allways ALSO show that post on a different blog.

That is why there is a blog all for example.
Have you looked at that ?

You said "you can allways ALSO show that post on a different post."

Do you mean post on a different blog?

No, I did not look at that, and I don't know how use it.