Add HDs while preserving the data

I am a 10 years windows person with basic unix training (very basic).
I have a sco server where it originally had 3 physical drives. Drive 0 had to be replaced so I did that but because I am really new to Unix I was afraid to detroy the data on DRIVE 1 and 2, so I took them out when I loaded the new drive and installed the OS, etc. After 8 hours of struggle, I can now access the SCO desktop. Now I want to add back the other two drives and make the OS see them but not loose any data. I then need to install the original application (medical manager) and let that see the data on the two drives. First question: Is this possible and second question: how do i get the OS to see the other two drives, not corrupt the data-or files on the drives, and then reload the software?

Well it depends on what and how it was previously installed...
We now cannot say more since you "re"installed the OS...
Have you an idea of the previous installation? (especially the mount points and file systems...)
I wonder if you would not have more success in specific SCO group since your questions are more OS specific admin (even if basic) than Dummies Q&A
In order to follow the rules, if you wish this thread can be moved there...
All the best

I would like to move it to the SCO group as you suggested. ????

There you are...
Good luck!