Line weight issue while joining the elements

[KuberanBaskar]

while joining the two different line weight models, it shows single line weight.Please give me a solution for this issue.Thank you

[barthbradley]

Have you tried reversing the join order? You see, what's happening is the linework category of the object being joined, has been changed to the Parent Category of the object to which it is joined. 

Does that make sense? 

For instance: if you joined the Generic Model to the Structural Framing, the Structural Framing linework uses the Generic Model Parent Category line weight.  If you joined the Structural Framing to the Generic Model, the Generic Model linework uses the Structural Framing Parent Category line weight.