Blacklist IP file for IPFW?

[Andreas X]

My /etc/rc.firewall file contains the following additional lines created by
me, for purpose of banning attacker's DDoSers IP:

        ${fwcmd} add deny ip from 122.228.19.80/24,\
                                  185.234.219.65/24,\
                                  92.118.38.57/24,\
                                  185.36.81.143/24,\
                                  141.98.10.137/24,\
                                  45.125.66.144/24,\
                                  185.100.87.190/24,\
                                  45.142.195.6/24,\
                                  45.143.223.52/24,\
                                  103.7.10.131/24,\
                                  52.178.192.68/24,\
                                  80.82.77.33/24,\
                                  164.68.112.178/24,\
                                  81.95.5.34/24 to any

The list dramatically grows each week. How may I create a text file so that
IPFW would fetch these IPs from there directly? What's the simplest way to
do this please?

P.S: I found no reason to *hide*/mask those IPs above, because they're
truly and randomly filling log files, not regular users at all! It'd be
useful for anyone else to know about them to block them too :)

Thank you all, so much!