Composition dealer scheme

In theory, YES. Rule 5(1)(c) of CGST clearly states "the goods held in stock by him have not been purchased from an unregistered supplier and where purchased, he pays the tax under sub-section (4) of section 9"

However, I dont think people will voluntarily do that. Legal practitioners will question the meaning of unregistered supplier, whether it means unregistered under GST or unregistered under old laws.

In case, you wish to do that, you need to issue a tax invoice upon yourself pursuant to section 31(3)(f) of CGST Act. The details must be furnished clearly in the GST return under relevant column