From the general regulations - 15G:
QUOTE
g) Candidates may use their discretion regarding indications or markings (particularly editorial) in the music – e.g. metronome marks, fingering, bowing, phrasing, the interpretation of ornaments, etc. – which need not be strictly observed. Where no such indications are present in the music, candidates should use their discretion to achieve a musical performance.
From the strings regs:
QUOTE
Candidates are not compelled to adhere to the fingering and bowing marks indicated: any good practical fingering and bowing will be accepted
So do what you like