The thing is, your scenario wouldn't actually happen.
Now yeah I'll admit I'm not as well versed in that area as others, but the idea the described church has NO ONE from a Catholic background seems pretty far fetched considering how diverse of backgrounds they consist of here. So for a more realistic one say it happened while studying abroad for a year in the US, baptizing people raised Catholic here certainly isn't uncommon.BRTD, it isn't all that common here either. Keep in mind you are the 0.1%.