Slitherine

I have a couple of questions about the timing of expanding into overlap for the non-active player.

Two different situations arose in a game last night.

1) Two units (A and B) were locked in combat. Unit A belonged to the active player. In his maneouvre phase the active player moved a third unit (C) into an overlap position.
a) Can the non-active player (unit B) expand to meet this overlap?
b) If unit A had expanded before unit C had moved up (on the opposite flank) later in the maneouvre phase could unit B chose which overlap to match?

2) Two units (A and B) were locked in combat. Unit A belonged to the active player. Both units had unengaged bases to the rear of those fighting. Unit A (active player) expanded on one flank and then moved up a unit C in side edge and front corner contact with the expaned base.
a) Can unit B match the overlap created by unit A expanding?
b) Must it do so when unit A expands or can the non-active plare wait until the active player has finished moving before deciding to match the overlap?

The timing in the second case was significant as unit B had an advantage against unit A but matching the expansion of A and allowing unit C to form an overlap would have been disadvantageous as unit C had a combat advantage agains unit B.

Conforming and expansions take place before other movement. So any BG that used a move to get into contact cannot have its overlap matched until a following bound.