Family of inscribed triangles having as equicenter and areal center two given points E, S

1) Take a point a in BC.
2) Let O be the midpoint between S and E.
3) Let A'B'C' be the reflection of ABC in O.
4) Let b' be the intersection between C'A' and the parallel to SC from a
5) Let c be the intersection between AB and the parallel to SA from b'
6) Let a' the intersection between B'C' and the parallel to SB from c
7) Let b the intersection between CA and the parallel to SC from a'
8) Changing a we can get all the triangles abc in the family.