You're using News.Individual.Net as your news server. NIN allows you to add a 'ID-MYUSERID' tag in the 'Message-ID:' header of your posts .
As far as I know, Thunderbird - your newsreader - allows you to score on that header.
In my newsreader (tin), I score on messages where my tag is in the last message-id of the 'References:' header, i.e. messages which are a response to one of my posts.
N.B. I do not know if Thunderbird allows you to generate your own message-ids, which is needed for the first step. If not, you'll need a different newsreader or a proxy between your newsreader and the NIN news server. (I use Hamster for that purpose.)
How topical. My fabulous, but ancient and decidely fragile, 40tude Dialog crashed (again) this morning. Been using it last century, which was also when it was last updated, so I won't recommend it, which is a shame as it'd satisfy your requirements and then some. As Dialog does, you could use a reader that 'scores' every poster you choose, eg, 'felix = 10', then all your posts stick out like dogs. Or you can simply colour your posts differently to the rest.
alvey Suspecting that the end of Dialog is near. Very near.
Thunderbird has a "between" column which might achieve that for you ... but it also has a hierarchy view -- but I am not certain if any of those will meet your need as I typically don't use either feature.
That my mathematical theoretical noumenon defines the meta-descriptor
prototypes which are prerequisite to the BEING of HOMO[iOS] SAPIEN[S|T]