Multiple Matching and indexing with null logic

See attached spread sheet

Part numbers listed in column A of sheet 1 need to get due date from both sheets 2 & 3. The date I need is the date in the prior row if the prior row has a date. If the prior row is empty, I need the date from the same row. Used match and subtacted 1 to get the prior row and index to get date. Need help with multiple sheets and also logic if prior date cell is empty. Actual data has 7 sheets with several thousand rows each. Thanks

Perhaps a macro? PUSH the green arrow in the file.