Dear Uwe, version 4.0 of sispmctl provides file examples/60-sispmctl.rules which could solve the problem.
https://github.com/xypron/sispmctl/tree/debian shows how to package sispmctl to create the group and copy said udev rules file. See file debian/sispmctl4.postinst and debian/debian/sispmctl4.udev. You will have to remove the "4" in the filenames. Please, package version 4.0 of sispmctl. Best regards Heinrich Schuchardt
