Joint Moves Wrong Part

[jresciniti]

Hello all,

I'm very new to Fusion 360.  Only my third day using it.  I have an STEP file that I downloaded and opened.  I copied and pasted a body in from another file, and when I try to make a joint between the bodies it will only allow me to move the original body to the part that was copied and pasted.  I can't move the part that was copied and pasted to the body.  The problem is that it then moves the entire model off the original center point so I can no longer mirror future modifications about the original axis.  

When I use the joint command, It will only allow me to select a face on the original body first.  I don't understand why.  Any help is welcomed.

[jeff_strater]

I think we need more info.  A video/screencast of what you are trying to do, and the model itself.  Most likely, this is easily explainable, but we'd need to see more to be sure.  Thanks.