However. I don't get where the old system only gave you one chance because it most certainly did not.
It was the same as now. Buy an extra badge get an extra chance. So each daughter plus myself would be banging on keyboards. Just like how now we each get an entry. If I wanted ten chances...get ten friends to bang on keyboards. Pay em each the ten bucks and there we go.
Now can we please get back to system credit?
Ah....you must not have used the old system where you didn't get a spot in the housing lottery unless you clicked on the submit button on housing day as soon as it went live. ONLY people who did that were considered for housing, it was roughly first come first served (roughly), and due to the lag and timing involved the number of badges one person bought was irrelevant as it was very difficult if not impossible to log in multiple times as soon as you could click the submit button.
Sure, you could get your daughters and ten friends to bang on keyboards when housing went live but for all practical purposes each was only going to get one spot in the housing queue- and to get that spot was still hit or miss and took a while, it wasn't a sure thing. This weeded out a LOT of people who didn't really want or need a room and made sure that it was one person, one chance.
By contrast, what they are doing now is giving 1 room chance per badge and telling you ahead of time if you should even bother logging in. This means that you, your daughters, and ten friends can each buy multiple badges and have exponentially more chances to win, and never even have to bang on a keyboard unless you actually know you are a winner. Indeed, you may actually win multiple times, all because the system is set up for this sort of abuse.
On top of that, keep in mind that between 2010 and 2015 Gen Con heavily expanded and promoted non-gaming events (non-gaming as defined by Gen Con itself, just to avoid another round of "God Emperor" nonsense). The side effect of this was the convention was flooded with more attendees coming for these events, doubling the size of the convention and heavily straining an existing housing problem even further right about the time that Gen Con implemented the current "Every badge gets a housing number!" approach. The side effect of this bloat was that Gen Con's core target audience started having severe problems with finding housing and price gouging- not cool. Note that this includes people actually running or helping with games that are hoping to be reimbursed- or who don't want to lug props and materials for a game they are running on to a taxi or uber, let alone around the convention center.
So we now have a system where attendees have a huge incentive to try to cheat the system and are rewarded for doing so. Unfortunately, adding in an ability to pass around badge codes with housing access attached actually encourages more cheating. This may not be the answer you want, and it may be annoying that it actually is tied into housing problems, but that is the actual answer. For what it is worth, I am not saying that you would personally be trying to do this to exploit the system.
That being said, I see no reason why you shouldn't be able to buy an existing badge holder system credit.