The short answer to this is yes, but you will need to run two merges - one to those with e-mail addresses, another to those without.
If you have a separate record for each contact, you will need
http://www.gmayor.com/ManyToOne.htm to list the contacts for each client. If the records have all the contacts listed in separate columns, you can use a conventional merge.
If you need to use the add-in, it will make things simpler is you copy the appropriate data to separate sheets.
You will then have the problem of what to do with the returned data. If you have some minion available to key the data into the worksheet then fine. If not then the aforementioned add-in can combine legacy form fields with mail merge, but this will only work for one to one merges i.e. the records must have one field for each contact, and not separate records. You could then use
http://www.gmayor.com/ExtractDataFromForms.htm to extract the form data to Excel.
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