I set wt.part.allowMultipleUsageLinkTypes to true with the following command:
xconfmanager -s wt.part.allowMultipleUsageLinkTypes=true -t codebase/wt.properties -p
Now i able to set parent and child constraints for my UsageLink soft type.
But "Insert Existing" action in Structure is broken now. I cann't add any exisiting part because searching is not working.