There is a dip in the driveway that leads to said garage and I was hoping to convert to you a makeshift living space for myself.

I'm debating whether I should go through the planning department and convert the SFR into an official duplex with the city.

You just need to understand what your buying, do great due diligence, have a plan incase the lagoon fails (new lagoons, convert to package plant, hook up to city).

Has anyone gone through the paperwork/legal process of converting a Single Family Home into a Duplex?

There did seem like there was a ton of potential in the walk-out basement as I could see an extra bed/bath being converted to it.Ultimately I would just like get him out of this mess. 

I have a few investment properties under my belt (converting primary residences into rentals), but am now looking into scaling up and doing my first partnership on a buy and hold condo, and looking for some advice on how to the structure the deal, especially from an equity/profit share perspective.  

DIY might convert your personal effort into some saved money in the short term, but you expose yourself to a pretty hefty, and expensive, learning curve should you mess something up.A couple articles I might recommend: questions to ask an attorney and risks of DIY LLCs.This isn't legal advice, just my opinion as a real estate investor.

The Tanglewilde-Thompson Place neighborhoods in Lacey are probably the best right now for finding (or converting into) a multifamily home.

However, if they do everything required of them, the holding fee converts to their security deposit and they get to move in.

@Wayne BrooksThanks Wayne it gives pretty good insight, it was a single family home but the previous people converted it into 2 family home because it was quite big could have easily be converted into 2 family legally but somehow they did not chose to and we bought it on auction, county court auction.