I think Sarla ripped off the papers that had Yuvraj's & Sandhya's name on it, and instead verified the papers were indeed in her name. If you noticed, she took the pile of documents Pankaj had sent her - property agreements won't have consignments mentioned in them, which these did. So what Sarla did was intersperse her documents in Pankaj's huge documents, but within the blue file.
As generally happens, when one is reading a long legal document, and has become comforable w/ it, one starts signing rapidly w/o reading subsequent pages so as to be done w/ the whole thing ASAP - it's not fun signing several pages of anything! So Puru, Prabha & Yuvraj, seeing the first few pages about the terms of goods transfers w/ customers, just went ahead and signed, and in the process, signed off their ownership of the haveli w/ it 🤣
Sandhya, look @ the bright side - it's no longer in Yuvraj's or Prabha's name 😆