In reply to James Richardson:
I suspect you'll struggle with 3 of you for a hitch in unfortunately, though you never know your luck...
Can't think of a taxi firm in braemar, but there are others up the glen that I suspect would run you along if pre-booked (for a price!). Give the hostel a call - they're likely to be able to advise better.
I wouldn't walk along the road personally, if you walk up to the duck pond you can pick up the birkwood trail on the south side of the glen, and link up various landy tracks in the woods till pretty much Victoria bridge over to mar lodge, then walk through the lodges grounds (no access issues) and pickup more landy tracks to lui water - cuts a good distance off the start!
normal post arwen caveats about blocked tracks apply! 🙂
cheers
stu