Where does the replacement child theory fail? If you can't think of the reason it fails, do you keep it as an open option? RC theory is really a form of abduction theory so it isn't anti-abduction, does that help you?
OK most say well "no other child died"? Well if there was a known child dying the replacement child theory wouldn't get off the ground would it, unless that was covered up too. It is getting complicated now.
A childless couple is more likely to steal a baby (usually, as there have been plenty other cases that are precedents for that). Has a childless couple ever stolen a nearly 4 year old to start a family? There could always be the first! I don't know how you bet that for an argument -the one off case.
So to me the RC theory is based on one child replacing another, not making a family for a childless couple.
IMO as a theory, it is a non starter. You are suggesting that a couple’s child dies and their first thought is, “must get another one, oh look there is a girl of a similar age.” It’s only saving grace from some quarters is that it means Madeleine is still alive, discounting the fact that it would mean another child died.
