  The second generation of stars in the GCs of the MW exhibit unusually high N,
Na, or Al, compared to typical Galactic halo stars at similar metallicities.
The halo field stars enhanced with such elements are believed to have
originated in disrupted GCs or escaped from existing GCs. We identify such
stars in the metallicity range -3.0 < [Fe/H] < 0.0 from a sample of ~ 36,800
giant stars observed in the SDSS and LAMOST survey, and present their dynamical
properties. The N-rich population and N-normal population among our giant
sample do not exhibit similarities in either in their metallicity distribution
function or dynamical properties. We find that, even though the MDF of the NRP
looks similar to that of the MW's GCs in the range of [Fe/H] < -1.0, our
analysis of the dynamical properties does not indicate similarities between
them in the same metallicity range, implying that the escaped members from
existing GCs may account for a small fraction of our N-rich stars, or the
orbits of the present GCs have been altered by the dynamical friction of the
MW. We also find a significant increase in the fraction of N-rich stars in the
halo field in the very metal-poor (VMP; [Fe/H] < -2.0) regime, comprising up to
~ 20% of the fraction of the N-rich stars below [Fe/H] = -2.5, hinting that
partially or fully destroyed VMP GCs may have in some degree contributed to the
Galactic halo. A more detailed dynamical analysis of the NRP reveals that our
sample of N-rich stars do not share a single common origin. Although a
substantial fraction of the N-rich stars seem to originate from the GCs formed
in situ, more than 60% of them are not associated with those of typical
Galactic populations, but probably have extragalactic origins associated with
GSE, Sequoia, and Sagittarius dwarf galaxies, as well as with presently
unrecognized progenitors.
