- Question: Why can a woman ask someone to light Chanukah candles for her if she forgot and lit Shabbos candles first but she can’t ask someone to make an eruv tavshilin for her if she forgot and already lit Yom Tov candles?
A. The Mishna Berura (679:1:1) says, if a woman is lighting Chanukah candles, since the custom is that we assume she accepts Shabbos as soon as she lights Shabbos candles, then she won’t be able to light Chanukah candles herself, rather she should ask someone else to light for her and he will say the first blessing for her but she can say the second blessing herself.
B. One can’t light fires on Shabbos.
C. There was a decree made that one makes an eruv tavshilin as a means to start cooking for the needs of Shabbos before Yom Tov which permits one to prepare food on Yom Tov for the next day of Shabbos as if preparations is being done for everything and you would not transgress the prohibition of preparing on Yom Tov for the next day.
Answer: Once she accepts upon herself Yom Tov by lighting candles then the whole concept of an eruv tavshilin doesn’t apply to her anymore because it only is applicable before Yom Tov starts but by lighting Chanukah candles the only issue is doing a melacha on Shabbos, transgressing Shabbos so someone who has not accepted Shabbos yet can light candles for her. (See Dirshu footnote 4 here.) [/edit]