The issue with a scarf being supported can be resolved with putting a timber under the scarf if it is located at a supporting concrete post. The timber under the scarfed sill over the concrete pier would be called a bolster. This supports the scarf at that pier location. And it can have a post over the scarf if the design is such.
see this image and the post could be your concrete pier.
https://pin.it/3YyN14y9e

Jim Rogers

Whatever you do, have fun doing it!