If TA does not address sale of property then you have to rely on the TA "cancellation" of lease terms. If there is none then you really need to think about offsetting the tenants costs to move and set up a new lease because the tenant can insist the lease remain in place and be transferred to the new owner.
I not lawyer/teacher/CPA.
You've been arrested? Law Society of Singapore can provide referrals.
You want an International School job? School website or http://www.ISS.edu
Your rugrat needs a School? Avoid for profit schools
You need Tax advice? Ask a CPA
You ran away without doing NS? Shame on you!