Setup a relationship between your main file and the file you send to clients. The relationship has to have, additionally to other criteria, a condition between a constant in your main file and a variable in the client file.
When client sends back the file, put it at the same place and do a relookup based upon the relationship. Obviously you'll have to setup your containers accordingly.
Only the fields (containers) depending both on your criteria and on the rejected condition should update, if you set up everything correctly.
thanks a lot for your prompt reply
is there a possibility to do this with Calculation instead of lookups? i am not so familiar with lookup.
after I get the file from the client. place it at the location of the related table. how do i trigger the process?