Why does the servant register on a Pesach by himself?

Question

Pesachim 8:2:

הָאוֹמֵר לְעַבְדּוֹ, צֵא וּשְׁחֹט עָלַי אֶת הַפֶּסַח, שָׁחַט גְּדִי, יֹאכַל. שָׁחַט טָלֶה, יֹאכַל. שָׁחַט גְּדִי וְטָלֶה, יֹאכַל מִן הָרִאשׁוֹן. ‏

שָׁכַח מָה אָמַר לוֹ רַבּוֹ, כֵּיצַד יַעֲשֶׂה, יִשְׁחַט טָלֶה וּגְדִי וְיֹאמַר, אִם גְּדִי אָמַר לִי רַבִּי, גְּדִי שֶׁלּוֹ וְטָלֶה שֶׁלִּי. וְאִם טָלֶה אָמַר לִי רַבִּי, הַטָּלֶה שֶׁלּוֹ וּגְדִי שֶׁלִּי. שָׁכַח רַבּוֹ מָה אָמַר לוֹ, שְׁנֵיהֶם יֵצְאוּ לְבֵית הַשְּׂרֵפָה, וּפְטוּרִין מִלַּעֲשׂוֹת פֶּסַח שֵׁנִי: ‏

If someone says to his servant "Shecht (slaughter) a korban Pesach (Paschal sacrifice) for me": if he shechts a goat, the master should eat it, if he shechts a sheep, the master should eat it. If he shechts both, the master should eat the first one.

If he forgets what the master said, he should shecht a sheep and a goat and say "If my master told me to shecht a goat, the goat is his and the sheep is mine. If my master told me to shecht a sheep, the sheep is his and the goat is mine." If the master also forgets what he said, both animals get burned, and neither of them have to do Pesach Sheini.

It seems that forgetting which animal one was sent to bring is common enough to be worth mentioning and ruling on.

Pesachim 8:6 lists several people who are probably going to be able to eat the Pesach that night, but who have a high probability of being disqualified. It rules that:

הָאוֹנֵן, וְהַמְפַקֵּחַ אֶת הַגַּל, וְכֵן מִי שֶׁהִבְטִיחוּהוּ לְהוֹצִיאוֹ מִבֵּית הָאֲסוּרִים, וְהַחוֹלֶה וְהַזָּקֵן שֶׁהֵן יְכוֹלִין לֶאֱכֹל כַּזַּיִת, שׁוֹחֲטִין עֲלֵיהֶן. עַל כֻּלָּן אֵין שׁוֹחֲטִין עֲלֵיהֶן בִּפְנֵי עַצְמָן, שֶׁמָּא יָבִיאוּ אֶת הַפֶּסַח לִידֵי פְסוּל. ‏

An onein (who's close relatve died that day), a search and rescue worker, someone who was promised to be let out of jail, or a sick or old person who can eat a kezayis, we can shecht a korban Pesach for them. In all of these cases, we don't shecht a korban Pesach for them alone, so that they don't disqualify it.

My question: Why not recommend that the servant in Mishnah Pesachim 8,2 do the same thing as in 8,6? That is, he should find at least two other people willing to cooperate, and register one on the goat and one on the sheep unconditionally. That way, even if the master forgets what he said, not one of the korbanos would be disqualified and burned.

Answer 1

The Rambam Hilchos Korban Pesach 3,2:

באומר לעבדו צא ושחוט עלי וקבע לו ושכח העבד מה אמר לו רבו. והוא שיתן לו רועה של רבו גדי וטלה ויאמר לו שחוט שניהן כדי שתשחוט כמו שאמר לו רבך והרי אחד מהן שלך על מנת שלא יהיה לרבך בו כלום. אם עשה הרועה כך אחר כך יהיה אפשר לעבד להתנות כמו שביארנו
When someone tells his slave to slaughter a Pesach offering and the Canaanite slave forgets which one, If the Shepard of lambs and kid-goats gives him one of each and declares:
"Slaughter both of them on condition that if that one was what your master wanted that lamb/kid-goat should be his and the other should be a present for yourself on condition that your master does not own it."
If the Shepherd who owns the flock made such a stipulation to the slave that one should keep for his master and one should be for himself, then when the master declares which one was his, the slave can eat the other one.

We see from here that: Since the slave does not own his masters lamb/kid-goat, he cannot give permission to others to join the group of the lamb/kid of his master as his master didn't include him in the group. The slave can only own a lamb/kid-goat when given as a present from the Shepherd after the master tells him what he wants, then the other animal is his to use for his own Korban Pesach.

If the master did register the slave on his animal the slave cannot take another animal to re-register himself or others. Rambam Korban Pesach 2,9:שָׁחַט עַל יְדֵי בְּנוֹ וּבִתּוֹ הַקְּטַנִּים וְעַל יְדֵי עַבְדּוֹ וְשִׁפְחָתוֹ הַכְּנַעֲנִים וְהָלְכוּ וְשָׁחֲטוּ הֵן לְעַצְמָן יוֹצְאִין בְּשֶׁל רַבָּן: i.e a slave once enumerated on the masters lamb cannot register himself on any others on a lamb even that belongs to him.

So the slave cannot register people on two lambs at the same time rather only on his lamb (when not included by the master) or only on his masters lamb (when included See Pesachim 8,4).