The thing is that systems that you buy off the shelf you can use in two ways. you can use them as they are and accept any imperfections but at least you know they work properly or you can customise them and risk making a complete horlicks of the whole thing. In general, unless there is a really pressing reason to customise a full system, you shouldn't do that and adopt processes that use the system rather than adapting the system to fit your processes.
I don't know for sure but I suspect the Seatgeek system is something we've taken off the shelf and have made some configuration changes to, which reflect our branding, but maybe haven't done much customisation on. The fact we've not been able to migrate Friends & Family certainly reinforces that view.