I have a spreadsheet with a column of names and email addresses.  I have to
replace these with a last name and first initial that can be found on another
worksheet.  The problem is that each cell contains more than one name and/or
email address, and they all have to stay that way.  So, for instance, if I
have all of the following in cell A1:

John Smith, Jane Doe, F. Smith, agreen@xyz789.com

I want to get the following result also still in one cell:

Smith, J, Doe, J, Smith, F, Green, A

The other problem is the way that the data is set up on the other worksheet.
It is set up like this:

John Smith             Smith, J               jsmith@abc123.com            
J. Smith
Andrew Green        Green, A              agreen@xyz789.com           A. Green
Fred Smith             Smith, F              fsmith@xyz789.com            
F. Smith
Jane Doe                Doe, J                 jdoe@abc123.com              
J. Doe

The match might not be found in the same column every time, so I don’t think
a function like VLOOKUP would work.  I’m not sure that any of the regular
functions would work.  I think it probably needs a macro.

Is what I’m trying to do even possible?

Thanks in advance for any information.