Q. If a woman lit only one (Shabbat) candle instead of the customary two, does she now have to light in the future one more light?

A. Biur Halocho (263,1) quotes Pri Megodim’s opinion that even if only one candle was forgotten or neglected the penalty of adding one more light applies. Biur Halocho disagrees as this is only a tradition, we should be lenient and not impose any castigation. (see also Yesodey Yeshurun, Shabbos p. 137 for similar opinion and Shabbos Hamalkoh p. 145 for a dissenting one).

Horav Shlomo Miller Shlit’a agrees with the lenient opinion.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a