Hidden ticket combined with discount code on Eventbrite

Hi, not sure this is the right place to ask this question, but I’m trying nevertheless.
My organization (the Project Management Institute Switzerland Chapter) is using Eventbrite for event registration, and we are quite happy with it, but there’s one thing where we haven’t found a satisfying solution yet.
We have different fees for members and non-members, and the way we handle this is that there’s a hidden ticket type for members which is only revealed if they log in to the chapter website first, and then go to Eventbrite (some single-sign-on thing, not sure how it was implemented, but it works). We need to do this, as many members forget to renew membership, and this is the only way to check that they are still active members (manually checking is too much work).
Our members also get 2 discount vouchers each year for a discount on the event fee, i.e. they get sent a promotional code which is valid for 12 months, and which they can apply 2 times. Also this works very well (apart from the fact that the field to enter the promotional code scrolls off the screen when you scroll through the list of tickets, so many members overlook it).
BUT: the combination of the 2 does not seem to be possible, I cannot apply a promotional code on a hidden ticket type.
This is super-annoying, does anyone have an idea for a workaround? How can I automatically check that someone is a member of the organization, PLUS allow promotional codes?