When mapping custom fields to a subticket, such as in this example, is there currently a way to sync changes from the parent ticket’s custom fields?

Currently, if the custom fields on the parent ticket are updated, the subticket does not reflect any of the changes. I would like to be able to “link” the custom fields to the subtickets so when the parent ticket is updated, the subticket automatically fetches the new custom field values. I am not interested in pushing the values back up to the parent ticket. The reason for this is that I am using lots of custom fields and their mappings as part of our on-boarding/off-boarding processes. Having to go into each subticket and manually update fields like the start and end dates is tedious and time-consuming.