Don't know if you've acted on this yet..... but best advice is to let a pro deal with this at this point.
Having said that, if it were me - this is what I'd do:
Presuming that "the boys" took off the timing belt, but did NOT do anything else with the engine (DID NOT rotate the crank or either cam shafts)........ I would put the old belt back on as closely as possible to the existing position.... including the tensioner.....
And with the plugs removed, manually rotate the engine with a wrench on the crankshaft bolt...... all the while making sure you don't feel contact of valves with pistons. You will likely be able to do this without interference, even if the belt might be of by a tooth or so. Care is advised in this process.
Using this method, get the crank at TDC with the cams in the correct (or approximately correct) position; understanding that the crank goes around twice before each "proper" positioning of the cams. Follow the marks prescribed in manual or video instructions to get this right.
Once you have the "correct" TDC position with the crank, the cams will be very near correct position. Take off the TB, and then 'nudge' the cams to the correct position (if they are not already there). Do NOT rotate cam shafts significantly.... just slight "adjusting" nudge (if required) to get the marks on target.
THIS is your starting point. Now you can proceed with proper installation, being sure to check all marks (crank & both cams) after you've finished the TB & tensioner install. You should be able to find ample instruction on this. Have your plugs out during this entire process to reduce compression resistance & give you a better feel for what's going on, and to better allow precise positioning of cam shafts.
I'm fairly sure your main query is whether it's safe to rotate shafts seperate from one another; and the answer is definitely NO! But if they haven't already been rotated separately, you should be able to put the belt back on & move them in sync, if care is taken with this process. This is one heck of a lot easier than removing the heads! But if someone already rotated these shafts independently to any significant degree.... all bets are off for an easy realignment.
Good Luck! I'm thinking you'll be fine if you just remain cautious. If you don't understand the 2x crank turns for each 1x cam turn... you might not want to attempt this.
