matching data associated with dates when the date columns are incomplete and dont match

I have four sets of columns. Each set has a date/time column and another column with a number. The date/time columns are incomplete (many dates are missing from each column). I want to add all the numbers in the number column that occur at the same time (within an hour). if there is no date/time, I would assume the to be zero. Do I need to make each date/time column have every day and hour first? How? Spreadsheet is attached.
Thank you !!!
DB

Could you just use a pivot table and group by the hour?

See my upload - i have only pivoted the first columns in sheet 2 - grouped by day then by hour....
can always ungroup by day if you don't want that part...

Seems to give what you are after though?