Lmaanachai: How are you going to draw a line between who is “Chasidish” and who is “Litvish”? Many many people don’t neatly fit into only one category. For example, those who are sometimes called “Heimish” could be more Chasidish leaning or more Litvish leaning, but not really either. There’s the Oberlanders, who most are more Chasidish leaning, but not Chasidish and not Litvish. They might even daven Nusach Ashkenaz while wearing an up-hat (or even a shtreimal). The Yekkes are neither Litvish nor Chasidish. Same with the Sefardic. And Teimanim. And Mizrachim. And what about the Yeshivish? A large portion, perhaps even a majority, shtam from Hungarian or Polish or other non-Litvish backgrounds.
When you have young girls getting engaged, if your proposal became reality, they’ll simply self-identify as non-Litvish.
My contention is that there’s no real way to implement this idea. If it were tried to be implemented, almost anyone who wanted to get around it would have so many loopholes to blast through.
And there will be wedding halls that will cater to young Kallahs, without them penalizing them, monetarily or otherwise.