in the section of the k-1 where you enter the acquisition and disposal dates the acquisition date doesn't matter because only the ordinary income recapture is entered here so dates have no effect on taxability
the gain or loss on sale after adjustment of your tax basis as per the supplemental schedule only goes on the 8949.
so compute you gain on all shares and multiply this by the long-term % if each lot is not detailed in the schedule
on one line enter the proceeds from the long-term shares. you have calculated the long- term portion of gain or loss so you compute basis by the difference this is coded as type E - proceeds but not basis reported to the IRS (if multiple acquisition dates use the latest for these lots)
on another line do the same for short term but the type is C.
