Why no singular in birchat hamazon for "ours and all that is ours"?

Question

Near the end of the birchat hamazon there is alternate wording for the beginning of a sentence for eating at your own table, or that of another person, but the end of that sentence is always in the plural (see quote below), at least in almost all bentchers. The end of the Horachamon that I refer to is worded "ours and all that is ours". But this ending sometimes does not agree in number with the beginning of the sentence which can read “me and all that is mine" or “head of household”.

So the sentence can read like this, “May the merciful one bless me, all that is mine, ours and all that is ours.” But that makes no sense to me. If the end of the sentence should agree with the beginning of the sentence, why do bentchers not include a singular wording of the end of the sentence? Is the plural wording correct for some reason that escapes me or is there another more proper wording and what might that wording be?

(Related but different question: Why no singular when referring to one parent in the birchat hamazon?)

For example, from Artscroll pg 192:

Answer 1

I believe the intention of the plural is for when one blesses at least one other, such as in the siddur shown in the question there is in parenthesis a mention of one's father and mother. One eating alone who is not blessing anyone else, such as family members, would skip the words אותנו וכל אשר לנו.

Let us point out that the text (נוסח) of all berachos is largely fluid (but CYLOR before making any changes, because the essential parts can be very subtle), especially with the HaRachmans after the forth blessing. To quote the Abudraham:

ואומר הרחמן כל אחד ואחד כרצונו וכרצון שאלתו

And say HaRachaman, each as he wishes to ask (from G-d).

Answer 2

The Talmud requires a guest to add a blessing for his host in his blessings after the meal. While it provides a suggested text, old prayer booklets, especially Ashkenazi ones, include a different blessing which consistently appears with some minor variations as:

הרחמן הוא יברך את [אבי] מארי בעל הבית הזה ואת [אמי] מרתי בעלת הבית הזה ואת ביתם ואת זרעם ואת כל אשר להם ואותנו ואת כל אשר לנו כמו שנתברכו אבותינו אברהם יצחק ויעקב בכל מכל כל כן יברך אותנו כלנו יחד בברכה שלמה אמן במרום ילמדו עליהם ועלינו זכות שתא לנו למשמרת שלום ונשא ברכה מאת ה' וצדקה מאלדי ישענו ונמצא חן ושכל טוב בעיני אלדים ואדם

If you are the host, then you obviously aren't included in that requirement (ShuA 201:1).

If you are moved to say a blessing for yourself or your own family or the Yankees, feel free to say one. If you choose to look to the above text for some inspiration in composing your personal prayer, that's certainly not a problem.

(The fact that some printers in the last 200 years have invented some grammaticaly-inconsistent hodgepodge prayer chimeras is of little Jewish legal significance.)

Answer 3

Most siddurim present the plural ending of this horachamon to be said by all: Artscroll (pictured above), Koren, Metuda, and the new RCA siddur. The Birnbaum siddur seems to have the same trouble with that approach as I. Birnbaum puts the plural continuation in one paragraph with the plural beginning, separate from the singular horachamon, as shown below (from Birnbaum page 767). That is one solution to the issue of lack of agreement of number.