That being said if you are hiring a designer it all depends on the project, budget and complexity of the designs and selections.

Because parters essentially have to be "beneficiaries" rather than partners which is complex.

If you aren't 100% comfortable with how it works, and you're in a tenant-friendly market (i.e. more complex procedures), then you should work with a housing attorney who knows the process. 

I would like to continue building my portfolio with small multi family and potentially move into apartment complexes.

They don't go away with experience or money, but in fact get more pronounced the larger/more complex your deals or portfolio becomes.If those feelings hold you back, then maybe investing isn't for you in this season of your life.

I know everyone looks to split up a MF building like this into condos, but it is actually making the process of purchasing the units more difficult, because we would own 100% of the complex.

This all depends on the size and complexity of the project as well.

BUT Most of the properties in 4plex complexes where we do not have HOA -  as I have noticed are in complete mess.

The only way is a TRO, but the daughter must present a threat to the complex as a whole. i.e. breaking windows, camping in the common area, etc.

You can also take a portion of your higher cash flow from the one paid off to pay additional principal to boost your cash flow on the other as well (I don't have any experience with this but I have heard of people doing it).It all depends on how complex you are wanting it to be and what your risk tolerance profile looks like.