I have several large evergreens that have been in the ground for 2 to 3 years. The top half of the tree on 5 or 6 of them are noticeably "crooked" or leaning one way or the other. Would it be harmful to the trees to gently attach them and pull them to stand up straight??
Straightening an Already Established Tree?
When pulling a limb or trunk to (un)bend, make sure the items you use will not "girdle" the bark. I always suggest that people use a legnth of "dead garden hose" with a sturdy rope or wire run through it. The hose will keep the rope or wire from girdling (which will kill) the plant. Use a metal T-post from a farm or tractor supply store to attach the rope or wire. Use a 6' or 8' post, the 5' will not be sturdy enough.