Enhanced Sets of Heptominoes
Begining with the following diagram the remaining 103 pieces can form a square of side 28.
The first diagram shows a replacement for the 7x14 rectangle at the bottom right.
These figures show replacements for the whole of the 14x14 square at the bottom right of the first diagram.
Redesigning the bottom left square allows us to get solutions for other pieces.
Another rearrangement gives us solutions for other pieces.
Finally the remaining five pieces.