I have this idea floating around to build an extension on the property or a separate ADU and finance it myself prior to refinancing, but that might be a bold move this early on in my REI career. 

You mentioned the semiconductor chip factories in Sherman and Denison (suburbs of Dallas), and I'm assuming you're referring to Texas Instruments building out and renovating new semiconductor fabrication factories, which is absolutely true.

Hopefully, this first investment will launch our journey in real estate.Here are some criteria we have in mind:Not in downtown SacramentoClass C+ or B location, since we will be living in one unit (we just want a safe location)Units with shared walls, not ceilingsSeparately meteredFairly renovated or well-maintained (not a fixer-upper, but if one unit is renovated and the others need some work, we would love the experience of fixing and renovating)Can you think of any other factors we should consider?

Of course she loved socializing with her tenants, so that is a huge factor.

They are building new fourplex units and advertising compelling cap rates in their pro formas.

I invested a bit over 150k into it and it's worth about 165k (rents for 1350).The other house is a 1977 build 4/2, it's in a nice/quiet neighborhood. 

In the next six months, I'm focused on building my wholesaling portfolio to reach a significant personal goal.

Here's some context: The access to our properties used to be the main road until the 1970s when the city rerouted it to build a highway around our homes, giving this access to the landowner at that time.

I'm looking to build a MFH in the area and would like to know if anyone has done something similar.

My last suggestion is building your team is going to be crucial for success so hire a professional property management company as well.