The only built-in way to do that in 8 is by Copy and Paste.
The method is, first, open whichever surface you want to be expanded to include the contents of the others. This could be the lower left surface for example, but it can be any. Call this surface 1.
Next, open each other surface in turn, Copy it to the clipboard, then return to surface 1 and Paste (Paste Append is best), saying yes if asked to expand image 1. Do the same for all other source surfaces (31 in your case).
This is labourious and time consuming, and there is a catch. At each point, the whole of surface 1, and two copies of each source surface in turn, must fit in available memory (including virtual memory). So if your surfaces are large, this process will become progressively slower, and may for practical purposes grind to a halt.
But you can try it. It might be a good way to convince yourself to buy Manifold 9.