Dont get confused when you see a scholar used a fabricated hadith in any of his work and he himsself said that hadith is batil somewhere else. Most of the time in their early works they used those hadith and later time they changed their position about the hadiths grading. Mufti Husain already hinted something about kitabul kabair long time ago, but sadly sunniforum.com is totally down so cant share the exact info. And No, Baatil hadiths arent used in matter of targhib.