Fig 1. B and D draw during the Impact Phase; it's now Blue's Manoeuvre Phase.
Fig 2. Can Blue shift A and feed more bases into the existing melee with B in his Manoeuvre Phase, as shown in Fig 2 below? I say no (see rationale following picture). Clue - this example has nothing to do with Restricted Areas.

Rationale:
B feeding more bases into an existing melee
The second step in the Manoeuvre Phase is to feed more bases into an existing melee. However, A's position in Fig 1 prevents B from being able to place the shaded bases into the gap - there is insufficient space for B's shaded bases to fit at this point in time. We now move to the third step of the Manoeuvre Phase (meaning it is too late to do any more feeding in this turn).
Shifting A
A is permitted to shift up to half a base width to move into an overlap position against an enemy BG that is in close combat to its front. D is in close combat to its front with B. However, A's shift sideways to its left would not put it into an overlap position, as it would not be in side edge to side edge with B.




