Everyone needs to roll to see through an illusion, regardless of others' success in doing so.
Your Face's party members would need to roll to see if they are able to resist the illusion spell, but if they do so it just means they see through the illusion themselves-- others would have to succeed in their own rolls.
I don't recall any rule indicating that an illusion works well until at least one person sees through one, at which point the illusion is obvious to everyone. The text for resisting an illusion spell in general states:
The magician must generate more hits than
the observer for the illusion to be considered real. If
the spell is not completely resisted, the target is fully
affected by the illusion.
Emphasis mine. The observer is singular and limited, rather than any observer.
The text of the relevant spells also seem to suggest that everyone needs to see through an illusion individually:
TRID PHANTASM
(REALISTIC, MULTI-SENSE, AREA)
Type: P Range: LOS (A)
Duration: S Drain: F
Anyone who might pierce the illusion must successfully
resist the spell. Simply make one Spellcasting Test
and use the hits scored as the threshold for anyone attempting
to resist at a later point.
_
IMPROVED INVISIBILITY
(REALISTIC, SINGLE-SENSE)
Type: P Range: LOS
Duration: S Drain: F - 1
Anyone who might be in a position to perceive the
subject must first successfully resist the spell. Simply
make one Spellcasting Test and use the hits scored as
the threshold for anyone that resists at a later point.
Even if the spell is resisted, the subject might remain
undetected if she’s good enough with her Sneaking
Test.
_
PHYSICAL MASK
(REALISTIC, MULTI-SENSE)
Type: P Range: T
Duration: S Drain: F – 1
Anyone who might see through the disguise must
first successfully resist the spell. Simply make one Spellcasting
Test and use the hits scored as the threshold
for anyone that resists at a later point.
Emphases also mine. Using the word anyone suggests that any given individual needs to beat the threshold to see the illusion for what it is. That's not to say that there are no other ways one person can wreck the illusion (like telling everyone that it's an illusion), but a teammate knowing it isn't real isn't a problem.
