I just managed to figure it out for blueprints. I have created new component in my actor BP (Geometry Collection Component), and set Rest Colection to one of my geometry collections by default (you need to set this to something otherwise it wont work). Then it will let you turn on/off physics and then you can turn them on/off when needed. In construction script i have Set Rest Collection from variable and it lets me change to whichever collection i want
Hope this helps