Motzti Shabbes - Rosh Chodesh bentching
Question
If I'm not sure if I said Retzei on Motzi Shabbes and then I say Yale Vyovo for Rosh Chodesh which is for Sunday. So, clearly, he did not mean to say the Shabbos addition. Yet, does this perhaps mistake mean the whole Benching is invalid and need to repeat or can one go back just to the beginning of that Brocho or just add Rosh Chodesh and finish Benching since Sofek BErochois Lehokel?
Answer
Shalom!
Thank you for your question.
It appears that you are referring to the benching at Shalosheudos on a Motzai Shabbos that begins Rosh Chodesh. While you are correct that there is a dispute whether and when Ya'aleh V'yavo should be included, everyone agree that if either R'tzei or Ya'aleh V'yavo one was omitted, the benching is not repeated.