WordPress Gallery

Hey! I’m having some trouble using WordPress galleries, here is the deal:

I have a first post, and I inserted 3 photos inside this one, all using the [gallery] code to create and sort the thumbnails automatically.

Then, I have a second post with 3 other photos, also using the [gallery] command.

Now, I wanted to create a third post, in this one, I would like to insert the 6 photos that are already in my server inside this post’s gallery, so I can use the [gallery] command.

Is there a way of doing?

I tried the NextGEN plugin, but I’ll have to do this a lot of times and working with NextGEN would just slow my work down…