You name it, I have seen it in this category.We took on management of a portfolio of properties for a client, and were advised one was occupied by siblings that had fallen behind on rent.

Get one of your mom's siblings, cousins, or a friend to be trustee of the trust.

I have a sibling who worked for a huge REIT as an asset manager. 

As far as I can tell every HOA document has something like this one form or another:The term "single family residential purposes" also shall be defined as: (1) one or more persons related by blood, marriage or adoption, which may include only parents and their dependent children, siblings, parents or grandparents; or (2) by no more than two unrelated persons living together as a single housekeeping unit and their dependent children, siblings, parents or grandparents.See Article III Section 3.1 here as an example: https://1drv.ms/b/s!

Quick background on each member:Parent: Has plenty of capital and wants to invest it; does not have the desire to be out finding deals, financing, rehabbing, etc. and lives in a small market with minimal real estate activitySibling: Has limited capital, time is somewhat tied up in multiple endeavors though sibling does want to provide some help in the day-to-day as time allows.

I have 3 siblings and the properties were distributed evenly from his Living Trust.

While offspring and ancestors are prohibited persons whereby you cannot transact with them, a sibling is not.

So does my sibling have to have an LLC entity or can they just do a personal loan my CheckBook IRA LLC funds to do real estate - transfer from sibling personal bank to my IRA LLC bank?  

It doesn't matter if they are married, dating, just friends, or siblings.

I understand in Massachusetts, since my father did not leave a will, half of the estate would go to his spouse (my mother) and the other half would be divided between the children (my siblings, all adults) .