@AhmedWas We need to combine object to create any path operation because we can't perform path operations on grouped objects.
As you know grouped objects contains several objects/paths but can't perform any path operation on it like "Difference" operation, and we can ungroup if we want to move/change a specific object/path.
While "Combine" is combining all paths into one path and we can perform any path operation on it.
You can "Combine" them from menu Path >> Combine (Ctrl + K) and that's will make them one path, then do your desired path operations to that path, then perform "Break Apart" from menu Path >> Break Apart (Ctrl + Shift + K) and colorize the objects/rectangles you want, then group them.
I usually do this in retro T-shirt design. When I need to cut out text from a colored sunset, I do this:
- Convert text to Ptah by "Object to path" from menu Path >> Object to path (Ctrl + Shift + C).
- "Ungroup" the text (Ctrl + Shift + G) then "Combine" it (Ctrl + Shift + K) to make it one path.
- Make a "Duplicate" (Ctrl + D) of the sunset to work on because we need the original later in colorizing.
- "Ungroup" the pieces/paths of sunset (If grouped) then "Combine" them (Ctrl + Shift + K).
- Put the text (Which is a path now) over the sunset and hold "Shift" on keyboard with the text selected then select the sunset and choose menu Path >> Difference (Ctrl + -).
- Now "Break Apart" (Ctrl + Shift + K) and start colorize each piece/path with colors you want then group them.
Here is a a video explains it (I didn't combine all the sunset pieces/paths because I want to cut off the text from the two middle pieces only):