Halflings are mortal beings who have mixed-race parentage.
Halflings are always mortal (rather than immortal), regardless if they have elvish blood or not.
Although only pure-blooded elves are truly immortal, however, those with mixed elvish blood live longer and stay looking young much longer than other mortal folk.
Elves do not typically acknowledge any children that are born of mixed parentage.
Dwarf halflings are usually acknowledged by their clans. However, dwarf halflings are subject to a fair amount of open bigotry, and generally considered “lower beings” due to their mixed ancestry.