Unsure if § 577a BGB applies...Landlord selling property

Our landlord intends to sell the rental properties that are part of the small neighborhood we live in. We are unsure if § 577a BGB applies to our situation and are trying to figure out how much time we have remaining in the property after a sale. A few details:

• we have lived in the property for over 5 years and have a permanent contract.
• the property is one of 11 townhouses that form a small neighborhood and are all owned by the same landlord.
• there are shared services that are managed by the landlord (trash, landscaping, driveway gate maintenance, etc.) as part of the warm rent.
• the townhouses were all new builds when first rented and we have been the sole tenant for our property.
• the landlord is listing and selling individual townhouses, not the entire grouping to another real estate investor.
• we have been given the right of first refusal in writing by the landlord.

At a minimum, we figure we have 6 months after a potential sale if the new owner claims Eigenbedarf. What is unclear to us is if the sale constitutes an initial separation of the larger neighborhood, and as a result, if the 3 year lock-up in § 577a BGB applies.

Any insights are greatly appreciated!