Adding slow mo videos to iMovie on the iPhone.

I have taken several short videos of skateboarding using slow mo, and then edited them using the photos app to adjust the slow motion to a certain part of the clip. For example, the first few seconds are regular speed with a 2-3 second slow motion part, and then it goes back to regular speed.

my problem is when I add these videos to iMovie to make a video with several of these clips, iMovie adjusts the slow motion settings I already edited in Photos. I just want the video I edited as is to be added to iMovie. After already editing them, I now have to edit them all again after adding them to iMovie instead of it just pulling the video as it is in photos.

how do I keep iMovie from changing the position of the slow motion part of the videos?