Ask current owners to demolish the unauthorised construction done 

2) only then enter into lease for 30 years or so 

You need to contact a local lawyer in USA 

The anti encroachment laws of your country and that of India differs, hence you may better seek guidance from your own attorney in the local and proceed as suggested

If the laws of your country allows the person who encroached your portion to get into a lease agreement, then you can cautiously take actions for such agreements so taht you don't lose the rights over the property that is owned by your housing society

You may engage the services of an attorney hailing from state of Washington who practices in civil laws involving the subject matter for better guidance and reliefs. 

- As per rule , the approval from the competent authority is necessary before raising high wall 

- Further, no structure  of   any  kind  whatsoever  temporary  or   permanent  shall  be  erected  or fence/partition  put  up  on  any common  area.

- Further, anything that alters the façade of a building is generally not approved unless expressly passed in Annual General Meeting by the society.

- Hence, if that expansion of the wall is without taking the approval of the society , then it will termed as encroachment and it can be demolish by the society or competent authority.

- However, you  can grant the house to the new owners for long term lease , as only the wall is having encroachment not entire portion of the house. 

- It is suggested to take suggestions from a local lawyer before entering into a lease agreement. 

Dear client,

The landowner allows the land for lease for 99 years which commences from the date the allotment was conducted. Prior to moving forward, it's important to carefully examine the HOA's governing documents to confirm that there are no particular provisions that forbid or limit such arrangements. It's recommended to consult with legal experts to ensure that the lease agreement is legally valid and safeguards the interests of both the HOA and its residents. The agreement should receive approval from the HOA board and potentially from the HOA members, contingent upon the bylaws and regulations in place.

After completion, it might be necessary to register the agreement in the property documents to inform future owners and safeguard the interests of all involved parties. Maintain transparent communication with the impacted residents and community members to ensure openness and handle any issues or disagreements that may arise.

Thank you.

Yes you can do the above lease