Debbie Reynold's Son Todd Describes Her Last Minutes

Debbie Reynolds' final wish was to join her daughter Carrie Fisher after death, so she went to sleep surrounded by family members and never woke up ... so says her son Todd in a new interview.

Todd will appear on a special edition of 20/20 Friday in which he describes Debbie's last few minutes. He recounts the story he told us ... Debbie said she wanted to be with Carrie -- 15 minutes later fell asleep, suffered a stroke -- and just a few minutes after that, he says "she technically was gone."

TMZ broke the story, Todd and members of his family hope to plan a joint funeral for the mother and daughter ... and were spotted at Hollywood Forever Cemetery Thursday scoping a possible location.