I’ve been wondering if "That is what….," and "This is what ….," in the following passage (taken from Fieldfish.com) can be used interchangeably.
Imagine you are an unmarried couple who have been trying to conceive for years. With the help of a well-established fertility clinic and donor sperm you undergo IVF treatment, and have your much desired child. In the course of the fertility process you are told both parents need to sign consent forms that once signed will confer on both the biological parent and the non-biological parent, the same rights of parentage without needing to go to court after the birth to get a declaration of parental responsibility, nor adoption orders. Then some months later the clinic calls you to tell you that due to an admin error, the forms were not completed correctly and the non-biological parent is not legally the child's parent, and probably the only solution is to go through the adoption process.
That is what happened to many couples in the UK who have had fertility treatment using donor sperm and eggs. This is what happened to a family in 2013 and it prompted the Human Fertilisation and Embryology Authority (the HFEA) to require all clinics to audit their cases to see whether there were any other failures by clinics of having failed to get the family to sign both consent form or, having lost or misfiled these legal consents.
“That” and “This” here seem to be almost the same. It is my understanding that “that” indicates a previously stated idea and “this” suggests the idea and something new about it. Is that correct? How does that affect how they are being used in the above passage?