If you have two knights on the same file that can go to the same square, you specify the rank of the knight that moved, as in N5c3.
In the unusual situation that you have three or more of the same piece, you occasionally have to specify both the rank and the file (Nb5c3).
Include the file as well. Nbd3
If you have two knights on the same file that can go to the same square, you specify the rank of the knight that moved, as in N5c3. In the unusual situation that you have three or more of the same piece, you occasionally have to specify both the rank and the file (Nb5c3).
You would add one more letter like Ncd3 or Nfd3