Hi Ray.
i deleted the existing single list using delprop, expanded the template and ran the svc -t bit. then, i ran the getprop to verify and it showed an empty list - as expected. next, i ran the setprop, expand template and svc -t. finally, i ran the getprop which now shows the 2 lists i wanted to try...
sbl-xbl.spamhaus.org:whois.rfc-ignorant.org
so i guess, long story short, any single additions to the existing list aren't possible and you would have rid yourself of the current list(s) and re-apply the new group of lists...
thanks for all your help Ray!
cheers,
--griz