In my opinion, service 859 should be amended as a Sembawang -
Sembawang Cres loop service and not going to Yishun due to
duplication with service 856 between Canberra Rd and Yishun
interchange. Service 856 can be slightly amended to serve Sembawang
Vista, Dr and Way for passengers transferring to/from service
859.
Yes, service 859 will be looping at Yishun interchange.