My apology for the delay.
You have to offer the sale to the tenants for the value that the purchasers are offering. I am assuming this is what the option to purchase clause says. If they refuse to buy then you can sell the other buyers with the tenants in the property.
There is very little that you can do unless the tenants agree to termination of the lease.
If they do not agree to ending the lease you cannot kick them out unless there is a breach by them.
You can only sell with the lease. If the lease is not registered it does not change the fact that they have a lease and they can enforce their rights.
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