I have dataset with few tables. Each table has unique name. One of the table will be used for dynamically grow portions inside the document, using the "Regions" option. All other tables will be used for normal mail merge operations.
in this case if i use MailMerge.ExecuteWithRegions(dataset) method, will it work for all other tables which are NOT used for "Regions"
No, the ExecuteWithRegions method will only try to merge regions in the document. The simple merge regions need to be merged using the Execute method. To simple mail merge all data from a DataSet you can iterate through all DataTables in your DataSet and call this method on each one separately.
If we can help with anything else, please feel free to ask.