For example set the path for the named directory in ISPConfig to another (existing) directory, that is not read by your named daemon.
I still want ispconfig to be able to add/edit domains, its just that i want it to add recursion no; in the options in named.conf and not remove everytime ispconfig updates the file
Yes, thats why you should backup all manually changed files before you update as ISPConfig is not able to compare the files and patch them as needed when they are incompatible with new functions introduced in a new ISPConfig version.