1. If one forgot to say Ya’aleh Veyavo in the morning Amidah and has already said the Additional service, some say that he does not need to repeat the morning service and others maintain that he does. In this case one should repeat it and make a condition that if he is not obligated to repeat it that it will be a benevolent prayer. (Mishne Berurah 422)
2. If he has already started the additional service and before he has finished the first three blessings thereof (before starting “Roshei Chadashim”) he remembered that he had not said Ya’aleh Veyavo in the morning service, he should change the prayer into the morning service, say Ya’aleh Veyavo and then pray the additional service. (ibid)
