In a message dated 4/12/99 1:32:03 AM Pacific Daylight Time, 
shihlin@pacific.net.sg writes:

	"Our friend died in a car accident, along with your father and two
 elder sisters...only you survived and since we were already your
 god-parents...we decided to take you in.  You were too young at that
 time to remember...Your real name is actually Akane Tendo. And this,"
 she paused before pointing towards the black-haired youth, "is Ranma
 Saotome, your fiancee."
 

Well, this is an almost typical train wreck of an ending.  I would like to 
point out that I dont find this one believable.    Here's why...  1) 99 
couples out of a hundred don't change a childs first name, even when they 
adopt.  2) its been made clear in the past that Amy's father no longer lives 
with Amy and her mother.  3)  Even being her godparents, I don't see how they 
knew about the engagement, and I for one wouldnt believe someone who just 
showed up at my door claiming that his son was engaged to my god daughter.

Yes, i know this is clearly an alternate history from the facts that you have 
put forward, but the holes i pointed out would still need to be plugged.  If 
you could, this would make for probobly THE most original SM/Ranma 1/2 
crossover idea I've yet read.