I recall a film where the mother secretly gets a job in the household of the son she has given up and helps to raise him. The truth is eventually revealed. Is this the same film you are speaking of?
In a strange kind of way it reminds me of the Orson Wells/Claudette Cobert movie "Tomorrow Is Forever". Of course it is nothing like it. In that one Welles plays Cobert's lost love. (The father of Cobert's son played by a young Richard Long) who has been reported lost in the war, but turns up 18 years later as a bearded cripple who hides the truth to spare all concerned the heartache of his belated return.
