Accessing sub-index levels in python pivot table

Question

I am facing an issue regarding pivot tables in python with multi index. For several indexes, I try to access the different items of the last index in order to freeze some values. For example in the screenshot, for each date, if its equal to a certain value (24/12/2020) I look for each ref in it (Ref0, Ref1, etc). If the Ref1 is in it, I freeze the values of 23/12/2020 for the 24/12/2020. So in the Ex1 I don't do anything but for Ex2, all the values (and columns) of 23/12/2020 will be the same as the one for 24/12/2020. I tried to loop on Value1 for accessing the corresponding indexes (with index.get_level_values()), but I don't see how I can know every items in Ref for each value. Can you please help me?

ps: their is only one unique date for each index of Index 3. So once I have done what I want, I move to the net Index 3

Thanks a lot.

[Python_Multilevel_PivotTable]