An investor group could form a Series LLC as the parent, or umbrella, holding company for all the properties. Not all states permit Series LLC structures.
A Series LLC allows the members to form a single LLC while separating assets into different "Series". In this company structure chart, there is a series for each property investment.
Structured properly a Series LLC insulates the assets of each Series from the liabilities of the other Series.
To illustrate, here is a contrasting limited liability company which owns multiple properties directly.
If a calamity strikes the multifamily property, injuring many of the tenants, the liability could exceed the value of the property.
In the second organization chart, the plaintiffs could reach the farmland, commercial building, and forest land because they are all assets of the LLC.
In the Series LLC chart, however, the plaintiffs could not reach the assets of the other Series (farmland, commercial building, and forest land), because they are isolated in a Series.
You can read more about real estate investment with limited liability companies.