Solution
You can certainly replace a part of 2D array with a smaller 2D array, using Replace Array Subset.vi. Refer to the following example.
Note: This image is a LabVIEW snippet, which includes LabVIEW code that you can reuse in your project. To use a snippet, right-click the image, save it to your computer, and drag the file onto your LabVIEW block diagram.