programmatically change permissions on folder in windows

Windows 2000 File server SP4:

Here is what we are doing:

If I go to folder> security> add <security group>
Then folder> security> Advanced> Permissions> Replace permission entries on
all child objects we get this dialog box

---------------------------
Security
---------------------------
This will remove explicitly defined permissions on all child objects and
enable propagation of inheritable permissions to those child objects. Only
inheritable permissions propagated from "FOLDER" will take effect.

Do you wish to continue?
---------------------------
Yes No
---------------------------
Here is our Question:

Is there any way to programmatically add a group to a folder structure and
all child objects without removing the values and permissions that already
exist on the folder structure and child objects? We do not want to remove
the permissions that were explicitly defined, we simply want to add a group
to the existing permissions.