merge multiple related fields into summary field

[rwhisnant]

First FM project for my business, can't figure out the following:

Have a case file which has information on each "case." Each case is divided into multiple parts (for example a,b, and c). The part file contains a text field and number of billing units for each part. (Case file and part file related by the case#.)

I created a field that adds up the total billing units for all the parts in a case just by Sum(related field). And I can display the related text fields in a portal on the case file. However, I can't figure out how to get the text fields concatenated into one summary text field.

I don't know if this matters, but I think I need it to not be done in a script, but hopefully in a calculation field, since i need it to update as any of the realated fields are changed.

Sorry if I haven't been clear- I'm new at this. Any help appreciated.