How to make constrained Thiessen polygons in ArcGIS Pro/QGIS 3.26 [closed]

Question

I want to make constrained Thiessen polygons in which the process of calculating polygons will stop when the each polygon touches the boundary line/coastline. How can I do it in ArcGIS Pro or in QGIS 3.26?

Here is an example:

I want these smaller parts of the red polygon to be part of the blue polygon. I've managed to do it manually with Singlepart to Multipart and than merging them one by one. Is there any way to automate this process?

Answer 1

1. Run multipart to single parts.
2. Select polygons that do not contain any of the points that were used to create the voronoi polygons.
3. Merge the selected polygons with the largest neighboring polygon.