dysfunctional i'm afraid :P

you can't use a literal : in the matchtext portion of an event header since mirc uses those to separate the fields. it's not sophisticated enough to recognize them as part of the regular expression

if you want to avoid using a capturing subpattern, as in (mother)? instead of (?:mother)?, you can use (?>mother)? as an alternative. (?> ) is called an atomic group and has a very specific function in regex; however if the contents of the group are of a fixed length as yours are, it is practically equivalent to (?: ) in that it won't create a backreference.