I think my point is very clear. I have no intention to relate J-7 to JF-17, they are very different planes, of course.
But you cannot deny that there are plenty of similarities between Super 7 and J-7, and between Super-7 and JF-17. Which only prove one thing, Super 7 is designed based on Sabre II (which again is based on J-7), and JF-17 is designed based on Super 7. Actually there are 3 designing phases of the plane as you have said: Sabre II (including China, USA, Pakistan) -> Super 7 (including China and Russia) -> JF-17 (including China and Pakistan), which makes it totally different compared to the original J-7. So why need similarities between J-7 and JF-17?
"The basic design of the airframe is a further development from the remains of the joint Sabre 2 project." does not mean JF-17 is a modified design of J-7.
Now some pictures of the original Sabre II and Super 7 model:
Sabre II
Super 7
Super 7
Wing modification of Sabre II proposed by Grumman
Engineers from Grumman checking on J-7M
J-7 -> Sabre II -> Super-7
Designing roadmap of Super-7 (1983~1993)