A350 GLA, MLA and DFS info
 

Please could I ask for the aerodynamic reasoning as well as a practical explanation of the Load Alleviation systems on the A350?

Load alleviation is designed to save structural stress and fatigue and therefore allow for lighter construction and longer airframe life.
I'm not sure if it has anything to do with aerodynamics as such.

MANEUVER LOAD ALLEVIATION (MLA)
MLA reduces loads during manoeuvres by modifying the spanwise lift distribution to reduce the wing bending moment. This is achieved by symmetrically deflecting the ailerons and/or the spoilers. For load factors >1.7 g, the ailerons are deflected upwards to a maximum of 20°. For load factors < -0.5 g, the ailerons are deflected downwards and spoilers upwards.

GUST LOAD ALLEVIATION (GLA)
The GLA reduces loads in the case of turbulence. The GLA reduces the lift of the outer wing by symmetrically deflecting the ailerons upwards.

DIFFERENTIAL FLAPS SETTINGS FOR LOAD ALLEVIATION (DFS)
The DFS modifies the spanwise lift distribution to reduce the wing bending moment at high gross weights. This is achieved by deflecting the inner flaps down to a maximum of 2 °.