Networkdays function with blank start dates

MFelix although I want to ignore any blanks in the 1st meeting column, I do need the dates for the 2nd and 3rd meeting for the customer, see example below of the output I need

Cust ID   1st Meeting   2nd Meeting   Day Diff 1-2   3rd Meeting  Day Diff 2-3

001         blank             1 Jan 2024          blank          5 Jan              4

002         blank             blank                   blank         7 Jan              blank

This is a summarised table, the original meeting table is very large and the meetings,  have been ranked, therefore the 3rd meeting is the most recent. 

Is there a way to show null if there is no date for the first meeting but still include the record in the table ?

Thank you in advance