This apparently isn't the move I'm looking for

I saw a movie a long time ago, on Lifetime, where the long-lost son shows up --I think maybe he was abducted as a seven or eight year old & ended up in a children's home. The mother is overjoyed that her son has come back. There is a younger sister too. I can't for the life of me think of who played the mom. Maybe Kate Jackson? The son seems to know everything about the family and has memories of grandparents, birthday parties, etc. But it all falls apart, they start getting afraid of the son, who has an explosive temper. It ends with the mom and daughter locking themselves in the basement laundry room with a last minute rescue by police. Turns out that the real son was dead. He had been in a children's home and had shared all his childhood memories with his friend, who was the same age and resembled him, before dying. The friend then decided to pose as the real son.