Particularly if they're side-by-side, look the same, look to have been constructed at the same time by the same company, share amenities and parking lot and gas meter, and maybe if the seller has put contingencies in place stating they must all sell together.It is not uncommon for an "apartment complex" to be a series of buildings, sharing a parking lot, amenities, etc., even the electric bill sometimes, and nobody would ever dream of parceling it out and selling one building at a time to different buyers.

For an older condo resort complex, unit slept 6, gross STR income was increased after renovations to between 30-35K per year.

One part is rent control and for now that only applies to apartment complexes with more than six units. 

After updating it should rent out at $870 (mirrored unit as the other that is at $870).I've enjoyed bringing this complex back to life and have a couple other options to do the same to others but would need to dump this one in order to do so.  

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.