[Avodah] Does a Bat Mitzva girl continue counting during Sefira

[Saul Mashbaum via Avodah]

In discussing the case of a girl who became bat mitzva in the course
of sefira, it is instructive to consider the analysis of Rav Yosef Dov
Halevi Soloveitchik (the Rov) of the Bahag's opinion on sefirat haomer
(see Harrei Kedem Volume II chapter 112).

The position of the Bahag is that one who does not count one day of
omer does not make a bracha on subsequent days

The Rov did not accept the widely-held opinion that the Bahag holds
that there is one mitzva to count all 49 days. Rather, each day of
sefira is a separate mitzva. However, on each day, there is a "din
mesuyam", a particular law that the previous days have been counted.
If this is not true, one is counting not sequentially, but with
skipping, not the count the Torah specified. Skipping a day
invalidates each and every subsequent day, not the totality of the
count.

As is well known, according to the Bahag, one who forgot to count at
night counts during the day without a bracha, but may subsequently
count with a bracha.

The Rov asked: according to the Bahag, does one fulfill the mitzva of
sefira during the day? If so, why doesn't one make a bracha? If not,
why may one continue counting subsequent days with a bracha?

The Rov held that the Bahag held like Rabbeinu Tam that the mitzva of
sefira is only at night, and when one counts during the day he does
not fulfill the mitzva of sefira at all. However, when counting during
the day, one does a "maase sefira", an act of counting, even if he
does not perform "mitzvat sefira". This maase sefira makes his
counting connected, and he can continue counting with a bracha,
although there was one day on which he did not perform the mitzva of
sefira at all.

According to the Bahag, one who forgot to count the 49th night gains
nothing by counting the following day, since one does not fulfill the
mitzva of sefira at all during the day. Counting during the day is not
in itself a mitzva, but only helps to enable counting subsequent days
with a bracha.

Even if one were to say that a katan (minor) does not have a chiyyuv
(obligation) to count sefira, and a katan that counts has not
performed the mitzva of sefira, nevertheless his count is a "maase
sefira", an act of counting. In this way the count of a minor is
similar to counting during the day; it is a masse sefira which enables
one to continue counting with a bracha, even when the katan becomes a
gadol.

Clearly, this applies to a minor girl exactly as it does to a minor boy.

The Rov noted that even if one were to know that he will not be able
to count every night until Shavuot, he counts every night with a
bracha until he misses, since each night's count is a separate mitzva,
and skipping a future night will not invalidate a previous night's
mitzva.

Saul Mashbaum