Combining Multiple Lines Into One Entity

Hello,

I am very new to DraftSight and currently working with very large DXF files and trying to import them into SolidWorks as a part. The DXF files are of trucks with all features provided from the manufacturer. The problem I am currently having is that because the DXF's are made up of thousands of individual entity lines, when I import them into a SolidWorks part it is drastically reducing the performance of my computer.

I understand there is a weld function in DraftSight which I have attempted at using to try and merge all of these lines into a single entity, but it hasn't worked, whether that's down to my own ability I'm not sure.

Ideally I would want to highlight entities that have been broken up into multiple lines and combine them.

Any help welcome, thankyou