BTW, time-remapping is greyed out? Dunno?
I'm not following you. If you move layer 1 from position a to position b in 10 frames and a to b is 100 pixels then a to b is moving at a speed of 10 pixels per frame. If you change the time from a to b to 20 frames then the movement from a to b is now 5 pixels per frame. The speed is cut in half.
If, on the other hand, you're rotating layer 1 at 10º per frame and it's rotating for 10 frames but you want to keep a rotating at 10º per second for 20 frames then you simply move the keyframe at frame 10 to frame 20 and add 100º to the value.
If you have a series of keyframes that you want to keep uniformly spaced but change the duration then select al the keyframes in the line, then hold down the Alt or Option (win or mac) key and click and drag on the last keyframe.
A better description of your project would help solve your problem.
One last thing, if time remapping is grayed out (unavailable) then that means the layer has no native motion (it's not video). You can fix this by pre-composint, moving all attributes, then applying time remapping to the layer. Time remapping will let you change the speed of everything on the layer uniformly.
I got it. Sorry. I pre-composed the layers, then used the graph editor to put in a 'keyframe hold' to extend the sequence and then another linear keyframe to move on to the next section. That way, the animation part stays the same and I am freeze-framing the last part to 'extend it' and then resume with a linear keyframe. Correct?
It looks ok now.