Keep keyframe proportionally with Change the length of a clip

Hello,

Is there a way so that keyframe of motion effects will move proportionally when I extend or short the clip?

For example, I have a photo and in the video effects -> motion -> scale, there is a keyframe in the beginning and another in the ending. If I extend the length of the photo in the timeline, the locations of keyframe will move, the beginning will stay in the same place, and another in the ending of the photo. The result will that the motion (scale) will be slowly than before.

Thanks,

Michael