As I understand your first option you had 3 Entities (A, B, C) and a single link table, but you didn't define any table schemas.

Lets assume each entity has a PK, int identity(1,1) The rest doesn't matter here.

This means each table will have PKs 1,2,3,4,5,.... etc.

The link table will then have columns

Entity-PK int -- Points bask to the entity

Count-Val int -- To maintain the 1-many relationship

Photo_Location

Under this model you can have the situation where the link table has rows

1,1,Path_A11

1,2,Path_A12

1,3,Path_B13

Where Path_A photos are from entity A, and Path_B photos are from entity B.

the query: SELECT E.PK, L.Count_Val, L.Photo_Location from Entity_B E join LinkTable L on E.PK = L.Entity_PK

will return photos from Path_A and Path_B which is wrong, it should only have returned Path_B13 !

You therefore need another column to identify which entity the photo relates to, or some other system such as different identity rangers at the entity level.

Cheers

Leo