Creating a lookup based on multiple requirements

Hello,

I have a very complicated problem that I can not seem to figure out. I have created a test sheet (attached) using generic values to illustrate my problem.

My problem according to the test sheet I have attached,

The coloured table on the left is my data. The table to the right, labled "Final DATA" is the final spreadsheet that I need.

I need to find a way to create the 'Final Data' table without having to copy and paste from each cell, because my data set is over 50,000 entries long.

What I need the table to show is the Number column from the left, and the date according to the following criteria. If entries in Step 2 exist, copy the LAST date associated with it. Otherwise if there are NO entries in step 2, choose the date from the FIRST entry in Step 1 from every number.

In this example sheet I have highlighted in Black the dates that I need. All entries that are step 2 that I need, I have highlighted Red. All entries that I need that are Step 1 are Blue. This generic data is just a small sample of the type of data that I am working with, I tried to include multiple examples in the list.

If anybody has any trouble understanding what I need, I will be happy to try and explain as best I can.

The "Final Data" I will be copying to a seperate worksheet, or workbook from the original.

Thank you,