[ASLML] ?? Multiple Advance into CC??

[EK I]

 hello List,

 can't find a reference to multiple advances requiring Ambush dr's into CC
in
 the same hex .  if infantry advance into CC in a building hex containing an
 enemy squad from more than one ADJACENT hex, is a separate Ambush DR made
 for each advance, or a single roll for all.  if separate rolls are made for
 each individual advance, and the first advance results in no Ambush but the
 second or third does, does that Ambush DRM apply to all susbsequent CC
 attacks, or just those made between the individual squads involved when
 Ambush actually occurred?

 many thanks - gt