Complex sentence: But when their mother faints as they pack, the family panics, only to discover that she is not ill, but is actually pregnant, and the doctor advises her not to leave the country, so the move is cancelled, much to Alex's delight.
Split into simpler sentences: But when their mother faints as they pack, the family panics, only to discover that she is not ill, but is actually pregnant. The doctor advises her not to leave the country, so the move is cancelled, much to Alex's delight.