I think I know what you want; if not, please re-post and clarify. Does the following example apply to your problem? Let's say there are two fields in the recordset that is being input to your report: FirstName and LastName. On the report detail line, instead of these two separate fields, you want one field: LastName, FirstName. To do this, in Crystal Reports, you would do Insert -> Formula. The "New Formula" window comes up, you name it, then the "Edit Formula" window comes up. For "Formula text" you would type something like this:
TrimRight({MyRecSet.LastName})+", "+TrimRight({MyRecSet.FirstName})
Then hit the Check button, then if all is well, hit the Accept button. You would then use this formula field instead of the two separate fields on your detail line.