How to Select Mutiple Regions in Godot 3.6 Tilemap

Godot Version

3.6

Question

Hi guys, I currently having trouble dealing with a a spacing tilesheet like this:
image

Instead of a bundled tilesheet like this:
image

I’m unsure how to select multiple region of a Tileset in “New single tile”, “New autotile” and “New atlas” modes because selecting another region individually creates a new tile mode. In Godot 4, there is a feature that automatically detects and separates regions, which works great.

However, I can’t upgrade to Godot 4 for some reasons, so I would really appreciate it if someone knows how to handle this type of tilesheet in Godot 3.6. All suggestions will be greatly appreciated!