Importing dwg is it possible to combine all the layers

[ngoldie]

Hi,

I have imported a .dwg file and the only way I was able to read it was to open it directly, which means I have all the layers of the file. I was wondering if there was any way to merge all of the layers into 1 layer so I can differentiate that drawing from my own?
I know there is File>Place external Drawing - however the file wouldn't import/open properly when I did this.

Thanks
Naomi