Buying DC converted land in full-extent

Land owner of a self-acquired agricultural property has applied for & gotten the DC conversion notification for the land. I also see Allenation sketch, but the Allenation doesn't reflect in RTC yet. No betterment charges are paid and town planning sketch and layout plan approvals are not in place. DC conversion notification clause 3 specifies that the raw land (sadari jameen) can not be sold without layout plan approval. However the owner (& planning engineer) contend that the said clause only applies if individual sites or part of DC converted land were to be sold to somone. Per them, buying or selling full-extent of land would not be a problem in future planning and approvals for layout. Also they say that this is standard approach to buy a layout-ready revenue land, as DC conversion ensures that no loans are pending on land. However, the clause in notification, verbatim doesn't seem to make any such distinction on sale. Please suggest if DC NOC/Permission is a must for purchase