How to change spacing between frames in existing grid of frames?

Hi, is there any way to edit the spacing between an existing grid of frames?

I am working on a document with a grid of frames where each of the frames are set to be like sided squares. I would like to edit the space between them while keeping the form of each frame as a like sided square. Therefore I cannot use the gap tool. Is there any way to edit the spacings in the grid after it has been created and filled with images? I would like to edit all of them at once naturally, not each spacing individually.

Attached is an example screenshot where the spacings are marked in case there is any confusion.