Way to extend a project by inserting space in middle?

let’s say I have a project that is 500 frames, with 10 objects/effects, very basic. I want to insert extra space, somewhere in the middle and inject 500 frames, filling that space with 1 new object I’m adding to the project (pausing the rest of the production until that newly inserted 500 frame animation is done), so the project is a bit longer. How do I insert extra space in the middle of a project, thereby extending the whole project by 500 extra frames, and not throw off any of the keyframes and timings?
It seems that if I try to extend exposure, the insert or override options just screw up anything after the space I create because I have keyframes that won’t move properly, or won’t let me move anything at all. Obviously, if there are no keyframe motions going, and all the objects start at the same frames, you can just drag a block of objects over to the right to accomplish this, but what do you do if there are keyframes and objects start at different frames? How do you move ALL objects over a few frames?

Yeah I had that question before. The only thing I could find useful (other than doing it manually by moving all the frames to the right to make room for more frames) was to use the X-Sheet, it seems that it has a bit more features for expanding frames.