List of shareholders in case of unlisted companies itr 6 of income tax

The ITR 6 for the A Y 2019-20 requires to provide details  of shareholders of unlisted company, this among others require the PAN of shareholders, No. of Shares, Date of allotment and issue price, date of sale or transfer of these allotted shares by the shareholder to others and PAN no. of that Buyer. It seems these details are to be given from the date of formation of company. Company might have allotted shares to some of the shareholders multiple times and at multiple price. some or all shares by the shareholder has been sold to others long back. The shareholder might have acquired shares by buying. under these circumstances giving all the details with PAN no will be a herculean task and may require lot of time and some time we may not be able to get all the required information which are old by more than 6 years or so. Whether any one is having any idea how to fill these details in ITR 6.