Thanks a lot brother. About the legal procedure, there is a big confusion all over. Like if you ask the eto office, they will tell you that prior to any such extension/ modification one has to ask permission from the eto office. But there is no example in the past that someone asked for the permission.
If you ask the ustaad's at city saddar road, who have extended thousands of such frames and still do it on daily basis, they reply "is ki ijaazat hai, koi permission ki zaroorat nahin".
And there are few who specify places from where you can have modifications in the frame, like it is allowed between the area covering, "the back shackle holder of the front leafs and the front shackle holder of the rear leafs". But this is still not confirmed.
I personally have extended four vehicles in the past but no one ever pointed it out.