database design - MongoDB architecture best practices for storing child relationships? -

say need store manager/employee relationship in mongodb database , sake of example lets these 2 different collections. try show relationship structuring documents/db this:

manager collection document:

{    id: 1,    name: "bill smith" } 

employee collection documents:

{   id: 1,   name: "abe smith",   managerid: 1 }, {   id: 2,   name: "hank smith",   managerid: 1 } 

but see people storing relationship in way:

method #2

manager collection document:

{   id: 1,   name: "bill smith",   employees: [1, 2] } 

employee collection documents:

{   id: 1,   name: "abe smith" }, {   id: 2,   name: "hank smith" } 

the drawback see second method employees array out of synch if employee deleted it's collection not array.

i'm curious if can point out pros/cons of 2 different methods , if 1 considered best practice storing child relationships in mongodb?

the mongodb blog post 6 rules of thumb mongodb schema design has discussion of topic , weighs many of pros , cons.

also search "mongodb embedding vs linking" , you'll lot of references , opinions.