Appending files instead of replacing when I select another files

I want to append dcm files to current viewer when I select another files, is it possible ?

The issue names no files, tests, or entry points, so first clarify the intended behavior for selecting another set of DICOM files in the current viewer. Agree whether files should append or replace, then identify the relevant file-selection flow and define completion with a reproducible multi-selection test.

Written by the indexing model from the issue text.