Fallout – Can you upgrade a room to merge it

I won't upgrade those rooms. You have later more than enough people to get others for hours in the training room. Buy 2-3 rooms and put the people in them instead one fast room. It's much cheaper and efficient.

By the way. You can further improve this. Just make a woman pregnant and put her inside the training room (not for the real world :D). This way you get more people while you train the existing ones. ;-)

INTERIM ANSWER:

I have been working on this problem since I started playing the game, and have come to an odd conclusion: "room types" might include having a full room (3 units) of each type.

I have tracked my Vault's progress on this spreadsheet, and have clearly indicated:

• The 19 types of rooms, and their 3 subtypes
  • e.g., the 3 levels for Diner are: Diner, Restaurant, Cafeteria.
• The number of each rooms I currently have in my vault.
• If 1 or more are present, a 1 gets placed in the "Present" column.
• This column is summed and divided by 57 (3 room types times 19 rooms), and presented as a percentage.

I honestly thought that once I had one of each of the room types, the achievement would unlock. However, this was not the case. At my current loadout, Game Center reports that I am only 40% complete for the achievement.

This has me thinking that not only do we require 1 of each room type, but they all must be of size 3 (many of my level 3 rooms are only size 1). I have now started tracking the sizes of my rooms. My next step is to get a size 3, level 3 of each room type and see how that affects the percentage.