The weekend was ugly, I must admit. However, having called Adee Plumbing on Friday, they sent out a plumber who found the leak, rented a small jack hammer, found the leak (update: there were two, next to each other) and fixed it. The concrete should be about dry now, so I'll be going by tonight to cut off a section of water-damaged drywall.
Fortunately, the carpet survived as it was not wet for long. Cathy's got a repair and cleaning place coming tomorrow morning, so the folks in #2 will be able to let their toddler run around again.
Although the ordeal will cost us upwards of $2,500 it is a blessing that Adee Plumbing is extending us financing options. Thank God!