Appending geometries smoothly

Hi,

I have a unstructured porous geometry. I want to create a new geometry with transforming and rotating existing geometry. Let’s say A to my first geometry. B is 90 degree rotated version of A. C is 90 degree rotated version of B. etc. I want to create a new geometry shaped like ABCD. I want to create continuity while merging these geometries.
To create continuous merging, My first idea is selecting a specific area from both faces like clipping tool. After that, I want to smooth only these areas. For example, I want to choose last 5mm of A and first 5mm of B. Then, I want to smooth ONLY these areas. While doing this operation, I do not want to disrupt my other areas. Do you guys have any recommendation for this job? Thank you very much. This is my first post for this forum and I am new at Paraview.

Thanks,