There are ways to help people know which person you are talking about

1. The person/thing + ‘prepositional phrase’
2. The person/thing + ‘participle phrase’

How to use the prepositional phrase

prepositions:
on, in, under, next to, by, with….

Use the noun (thing), then the preposition.

The child in the corner
The woman by the door
The man with the beard

How to use the participle phrase

participle phrases:
(do)ing …

Use the noun, then the participle phrase.

The child sitting in the corner
The woman drinking the wine by the door
The man speaking to the doctor  

For more detail, use both

Preposition phrases and participle phrases can be used together. The preposition phrase usually comes first:

The child with the lollipop sitting in the corner.
The woman with the long black hair standing by the door.
The man under the table hiding from the police.

Adding adjectives to the noun

For more detail, add an adjective to the first noun.

The ugly child with the lollipop.
The really tall woman standing by the door.
The cowardly man under the table hiding from the police.  

Exercises

Using adjectives, prepositional phrases and participle phrases, describe ‘which…’ for things in the room around you (example: the orange folder next to the blue book sitting on the table)