Vinaysingh,
You can export your existing relations first into a text file (old.txt), run your Excel analysis & generate the additional relations (new.txt), and then merge the two text files together before importing them into the Creo Parametric relations editor.
You can use the CMD/DOS "copy" command to merge the two files together.
The syntax is simple: copy old.txt+new.txt result.txt
If you don't want the users editing the relations that you generate via the Excel analysis, you can add comment lines into the relations as well. Something along the lines of:
/* Begin Excel generated relations.
/* Do NOT edit the following relations. They are generated via an external program.
MYPARAM1=55.3
MYPARAM2=YES
MYPARAM3="YES"
/* End Excel generated relations.
Using the comments at the beginning and end of the Excel generated relations section also has the added benefit of allowing you to easily remove the section either manually or automatically via a simple script.
Regards,
Dan N.