@garemoko this at minimum needs more definition / discussion. This brings us back to face the "activity definitions by reference or by value" discussion. Specifically, does this filter look at the activity definition that was stored with the statement, or consider what the LRS considers to be the cannonical definition of the activity instead?

See my comments above about the LRS itself not being a reporting system... This is certainly a "must-have" feature for a reporting system, but I'd rather avoid the confusion in an LRS