Will the CAM fees assessed on top of the rent to the office have some operations profit for administering the arrangement?

I'm not a big fan of most "silent partner" arrangements.

Do you want to pay a desk fee and extra upfront costs to have lots of materials and services at your disposal or do you want a more basic arrangement with all the fees based on transactions.

Maybe arrange your financing ahead of time for a second deal and put 30% down on another identical deal. you’ll still have half a million left for reserves or a third I dentical deal if you have other reserves. 

That shouldn’t be a major hardship on the owner or tenants, it’s the basic arrangement they have now but in writing so everyone is on the same page.

Or the loan could be taken out on a duplex, that is then later converted, with some other pay arrangements?

While under certain circumstances it might be possible to create a partnership between qualified plan and disqualified person there is always likelihood that  such arrangement may lead to a prohibited transaction.

If a meeting gets arranged please message me.

What are you current living arrangements?

The arrangement was for my sister to pay half the rent and my grandmother to live rent free (forever) in exchange for rights to her property.