Fabricated Traditions

Are there Shia Hadiths that claim the Quran was altered by the first three caliphs to erase the virtues of Imam Ali? If so, how are they explained by the scholars? Sayyed Mohammad Al-Musawi	How did unidentified narrators make their way into Shia books? How is it possible for fabricated hadiths from unknown narrators to be included in Shia books despite the scarce but true followers of the Imams? Amina Inloes
How can Shia claim to have acquired knowledge from Imams if there are many fabricated hadiths in the chain of narration between Imams and the authors of Usul-e-Arba'a? Or are all these chains of narration considered authentic? Sayyed Mohammad Al-Musawi	Why are there narrations in some books about Imam Ali (as) that suggest that he was bald and had a great stomach? Are these fabricated? Sayyed Mohammad Al-Musawi