Libration points with varying mass

A question was asked some time ago about the stability of the Earth-Moon
system if we move mass from place to place. I think that question was
answered well, i.e. the Earth and Moon are so massive that problem can be
ignored for centuries. But that discussion got me to wondering about L-4
and L-5. L-1 for a binary system of equal masses would be in the center,
and I can imagine if we moved billions and billions of tons of material from
the Earth to the Moon, L-1 would move towards Earth, arriving at half way
when the two bodies became of equal mass. But I can't imagine how L-4 and
L-5 would move in this problem. Does anyone know? Jay Huebner