Is it possible to have chemotherapy and tpn use the same line?

Not really: I personally prefer TPN to have its own line, and you will hear that from experienced nurses. While the substances may not be incompatible, TPN is associated with risk of infection in the line, so should really have its own, dedicated vascular catheter access, in my opinion. I suppose there could be situations where TPN and chemo have to share a line, but if there's a choice, they shouldn't.