You can convert the splines to polylines in Draftsight before you import with "explodex" and I´m sure the other software you mentioned can also do that, see here https://forum.solidworks.com/message/461690?sr=search&searchId=a2185729-bf77-4f0b-864e-c49d3252c6c5&searchIndex=0#461690
You can probably also export what you have already import by selecting "Export all splines as polylines" in options and import again.
Thanks Ingvar. This worked for me.
I just dont see "Solved" button