In my example, the line portion has data-points that represent 1 day each and the candlestick portion represents 1 week each…
My suggestion is to make the line portion match the time scale of the candlestick portion. Make each data point represent the same amount of time for the line portion as the candlestick portion (1 week).
Make the line portion compressed to 1/5th of the space.
Make 5 days of the line in to a different colored week candlestick (grey?) so we know the true high and low are not properly represented.