Word for something which is directly related to something else

Solution 1:

Associated items, persons, or places?

associated adjective: (of a person or thing) connected with something else. "two associated events"

synonyms: related, connected, linked, correlated, corresponding. see, Google

Solution 2:

Each of the items on your planning list is a element of the plan:

noun

1 An essential or characteristic part of something abstract

_ODO

Solution 3:

Accessory (noun):

a thing which can be added to something else in order to make it more useful, versatile or attractive.[Source]: ODO

Chalk is an accessory to the chalkboard.

Solution 4:

If you want to group items which have properties in common, could you not call these groups "categories". So, in your example, your categories would be "People"; "Food"; "Places". Or have I missed your point?

Solution 5:

English generally doesn't group people and things into the same category; nor does it speak of people as if they were part of the same category as things. "Businessman's English" or "corporate-speak" is willing to do this, though; for example, it abbreviates "human resources" to "resources" and uses the word to mean "personnel."

Given this, David Pugh's suggestion is a good one; if there's a word anywhere in English for a category of prerequisites that includes both people and things, it's most likely to be a term of art in project management.

If you don't need a single word and don't mind sounding stuffy, "associated entities" might work.

If you need a single word and don't insist on English, I think that Scholastic Latin causae can be used in the sense you're looking for. I'm not trying to insult you by saying that -- although I am trying to express how hard it is to find a matching English word...