Not currently. How are you thinking the filter would work in an abstract sense? You can estabilsh any external dataset as a mentionables set. Perhaps you can use an additional column in the data that informs how posts with custom mentionable data would be ordered. Then you’d also need to deal with situations where mutiple mentions were made in the same post. If you scoped out the feature in some detail in an abstract sense we could get a sense of how much it would take to implement it.