Subdividing Double Lot King County

[Heather Hopkins]

Hoping one of you BP'ers may be able to connect me in Seattle, Washington. I have a piece of property on a double lot, there is an existing SFR and grandfathered ADU on one side, the second side is just open yard. I am looking for some advice or connections to get me the through the subdivision process (lot split). Have any of you looked into doing this in King County recently or know an engineer who could help? I've found the process online via the building department but would like some feedback from others who are familiar with the process.