Loss/Gain of Coverage Enrollment End Date

We have a Supplemental Child plan that is allowed to carry dependents up to the age of 26.

Currently, when a child ages out, we use the Loss/Gain of coverage life event to end their coverage. This life event is set up to generally end all coverages for the > 26 dependent the end of the month in which the life event was triggered in, however, a new requirement is that Supplemental Life Children plan should end the date the life event is entered rather than the end of the month like all other plans.

I added the Loss/Gain of Coverage life event to the Child plan with a "Previous Coverage End Date" set to "Event," however, the plan is still continuing on until the end of the month. Can someone help me identify where in our configuration do I need to set up end as of event for >26 dependents, but carry forward the underage dependents on the plan?