I found, as a snippet, the following:
"...; Генерал-Майор Башуцкий в Петербурге 6 батальонов для гвардии и 18 для Финляндского корпуса. ...." which is exactly what you asked about. It is from Михайловский-Данилевский.
From my good friend Mark Conrad's excellent translation of Vol. 10A:
"22 November 1811– The Kargopol, Olonets, Belev, Chigrin, Novomirgorod, Yelisavetgrad, Olviopol, Ivanovo, Taganrog, and Azov depots, belonging to the 6th, 21st, 17th, 22nd, 8th, 10th, 16th, 13th, 19th, and 20th Divisions, were ordered to each have six three-company battalions, which received the name of fourth Rezervnye [chetvertye Rezervnye] or Recruit [Rekrutskie] battalions of those regiments to which they were assigned, and at this time all Recruit Depots belonged to divisions as follows: Vyazma – 3rd, Toropets – 4th, Kholm – 5th, Kargopol – 6th, Starodub – 7th, Novomirgorod – 8th, Izyum – 9th, Yelisavetgrad – 10th, Roslavl – 11th, Akhtyrka – 12th, Ivanovo – 13th, Staraya-Russa – 14th, Zmiev – 15th, Olviopol – 16th, Belev – 17th, Konotop – 18th, Taganrog – 19th, Azov – 20th, Olonets – 21st, Chigrin – 22nd, Yelna – 23rd, Novgorod-Severski – 24th, Podgoshcha – 25th, and Romny – 26th. Thus, only two Depots were not divided into battalions: the Yaroslavl and Bakhmut; and in the Army infantry only Grenadier regiments did not have fourth battalions. Along with these orders, the 1st and 2nd Reserve Divisions, composed of Reserve battalions, were called the 1st and 2nd Reserve Corps [1-i i 2-i Rezervnye Korpusa], and Reserve brigades were renamed Reserve divisions [Rezervnyya divizii] (46). "
So the Reserve Battalions mentioned are 3 company 4th Battalions - one for each of the six regiments in the designated divisions. No grenadiers. I did not find a similar order for the Guard regiments.
"Высочайший приказ .......................17 Марта. Прик. по полку 12 Мая. 
Формируется в Пскове Гвардейский резерв, в который определяются майоры пехотных полков Кегсгольмскаго Мордвинов и Рыльскаго Тиханов. Резерв сей делится на 6 равных частей: 1 для Преображенскаго, 2 Семеновскаго, 3 Измайловскаго, 4 Литовскаго, 5 Егерскаго, 6 для Финляндскаго Л.-Гв. полков. Командовать сими частями: первыми тремя майору Мордвинову, а последними тремя майору Тиханову." http://www.lgsp.petrobrigada.ru/index.html additional documents from this page concern also concern the unit.
This is what I knew previously. Six companies - one for each guard infantry regiment - were formed at Pskov and collectively called the Guard reserve. These are the units I mentioned in my previous post that were later sent to Wittgenstein.
Sadly, I have a folder with quite a few documents about the Guard reserve. In several consolidations of my papers I can no longer find the folder. I had intended to write an article about them, but 'sometime never comes' as they say in the song.
"... Кромѣ того находились: 1) Въ Финляндіи и Петербургѣ: 3 пѣхотныхъ дивизіи, 6, 21 и 25, всего 54 батальона, 10 эскадроновъ, 8 ротъ артиллеріи и 5 полковъ казачьихъ. ..."
So, yes, it should be the 6th division NOT the 16th. I am human - Urah! <;^}
I hope that takes care of everything.