Automatically Create List Of Column Contents Based On Criteria?

I have a spreadsheet that lists dates in row 6, columns V through BE. We use these dates to log attendance for kids, so under each date there may be one of many symbols, such as "x" if the student was there. I would like to create a list of the dates that meet one of two criteria: either blank or containing "WR". So, let's say column Z is blank and Y has "WR" in it. In column FB I would like a list of all of the dates that were blank or WR, so I would want the dates contained in row 6 for Y and Z. Is there a function that will 1) look for a blank or WR across a row, 2) find the associated date for that blank in row 6, and 3) write the in another column in the form of a list, each date separated by commas? Here is an example of my information. I would like for a function to automatically make the list in column FB for any dates that are blank or contain "WR".

V
W
X
Y
Z
AA
AB
AC
...
FB

[code]....

List of Dates Absent

x
x
x
WR

x
x
x

1/23, 1/24

[code]....