Apply Time Context to Other DRs in Event Frames

As this post points out, "The PI Point DR allows you to specify whether you want the StartTime or EndTime of the event frame. All other OSIsoft data references - most notably Table Lookup, Formula, StringBuilder - do not give you this option. Those other DR's are limited to only using the EndTime."

As the attribute I want to reference is a Formula DR, I want to use the String Builder DR in the EF. However, the attribute is an event code that can and will change over time (that's what's triggering the EF), so what's captured at the start time versus the end time of the EF will be very different. I need the option to choose which Time Context I want.