When using the Linux dgap driver, the file /etc/udev/rules.d/10-dgap.rules can be edited. A single line was changed from:

KERNEL=="tty_dgap*", PROGRAM="/usr/sbin/dgap_udev %k", NAME="%c", OPTIONS+="last_rule"

to:

KERNEL=="tty_dgap*", PROGRAM="/usr/sbin/dgap_udev %k", NAME="%c", OPTIONS+="last_rule", GROUP="uucp"

After a reboot the ports will have a group of uucp.

Additional UDEV examples can be found here:

https://www.digi.com/support/knowledge-base/how-to-preserve-device-permissions-settings-with-r