The structure of lithium halide with space group P63mc in MP?

Hi. I have a question about the MP database of lithium halide (LiCl, LiBr, and LiI).
I use MP for materials search in sulfide solid electrolyte.

The phase diagram LiX–P2S5–Li2S was obtained by Pymatgen using MP API,
but the values of LiX Ehull were always P63mc space group, not Fm-3m space group (Experimental).
I search the structure of LiX with P63mc space group, but there are no information…

Why MP select and compare the structure of P63mc instead of Fm-3m?
I know that the value of Ehull P63mc was zero.
Is it possible to modify the structure from Fm-3m to P63mc?
Is there any reference paper?

Please give me some comments.