It offers flexibility as a landlord to be able to offer more or less rooms as needed, protection to the landlord in that you can hedge with adding LTR or STR to the mix, and simplification to the business as your only dealing with one address.

Another key benefit is diversification; an SDIRA allows you to include real estate in your portfolio, reducing risk by spreading your investments across different asset types, which isn’t possible with a standard IRA.Moreover, assets in an SDIRA often enjoy protection from creditors, adding a layer of security to your investments.

To simplify the existing lease I thought about asking the tenant if they would be ok modifying the addendums to get rid of the resident benefit package and the building protection plan. 

Holding properties in an LLC (or other legal entity) can offer valuable protection for your personal assets, so I understand why you went that route.

Not only will this lead to you being alerted if the policy lapses, but if their pet bites someone it may protect you from a resulting lawsuit.4) Unathorized Pet- Check your lease and state laws to see if you can terminate the lease over this.

While an LLC offers liability protection, it does not change how taxes are reported unless treated as a partnership or corporation.

You certainly want to vet your property manager to ensure they are focused on balancing asset protection with tenant satisfaction.

How do I protect myself in this situation, while also helping a relative? 

Make sure your real estate agent isn't just about closing that one deal but understands the benefit of protecting you on each purchase to ensure that you keep buying because you are enjoying success.  2.

Where is vacancy, maintenance/cap ex, asset protection, PM (include it even if self managing as you deserve to be compensated for your efforts), utilities, misc.