2004 Ford Taurus heater core lines are leaking coolant?

2004 Ford Taurus heater core lines are leaking coolant?
Added (1). I was told today after an oil change and anti-freeze flush that my Taurus is leaking coolant from the heater core lines. I read that heater cores are very expensive to replace and am wondering if replacing just the lines is possible. Am also wondering how much that would cost
Added (2). Rephrasing my question (in case there's any confusion): Can I replace JUST heater core lines without having to replace the heater core? If so, how much will that cost?

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