Creating a part in an assembly

[hondarider09]

What is the easiest way for me to create a part while in an assembly? I understand I could create a component, but I already have the part modeled.

 

[s_pme20]

insert that part (assemble) in assembly..then right click on that part--> Activate..now you are in part modeling environment..take care while you chose reference for sketches....

 

[faisalmk]

As mentioned by Sachin Patel, insert that part then use top_down approach.