I would just add collision to the individual parts.
turn them into BP, add an on overlap event to a custom collision within the BP - or to the base model if it is made with good custom collision.
if collision occurs (on overla start) you get the parent, and tell it to stop normally via a cast to and changing a variable or calling a function.
When you add them to the pawn BP they’ll become child actors.
Try this out with a simple BP and sphere collision at first. Make sure it works with your current setup.