I may not completely understand your scenario, but A better practice might be to just create accounts for parents and put the parent email addresses on those accounts. You don’t have to give those parents access at all, but it’s nice to have that parent info in one place. Make sure those parent accounts are in the same household as the child. You can then go to Manage > Settings > Edit Troop/Pack settings, and under “TroopTrack Settings” you can mark “Copy parents on all scout emails” and then you will be all set.
If you’d like to make an admin feature for the secondary emails, please request it in a separate ticket under the “Ideas” category so we can gage that idea on its own.