Modelling a college might produce this parent-child table chain ...
state
county
college
school
department
course
class section
class datetime
instructor
In addition, various levels in this entity chain might rely on different computer services companies ...
state <------------------+
| |
university <----- computerservices
| | |
school <---------------+ |
| |
department <--------------+
|
etc
It's not incorrect to regard computerservices as a parent of the entities that reference it, ditto for, say, janitorservices, varies contracted services &c. All those relationships are potentially 1-many candidates for foreign key declarations.
For analysis of the requirement, though, it can be useful to differentiate kernel relationships in the chain from such lookup relationships. For example, all the entities in the state...instructor chain will be governed by civil service rules and conventions whereas some lookups likely will not.