If only your name appears on the title deed and their names only appear on the bond, then it means that if you do not pay the installments, the bank can hold them liable for the payment of those installments and the bank can hold you liable as well. So, you all will be liable for that debt. You cannot, however, make them pay off the loan on your behalf since they are sureties and not the principal debtor (which you are). Their obligation to pay only starts when you don't pay.
The fact that their names does not appear on the title deeds means that they only have obligations towards this property and no rights. They cannot, therefore, claim ownership of this property, since they are not the registered owners of this property (since their names are XXXXX XXXXX the title deeds).
So, if you pay off the bond and the bond is canceled, all that means is that they would be absolved from the obligation to stand surety for your debt towards the house.
In short, since their names are XXXXX XXXXX the title deeds, there is no way that they can claim any form of ownership of the property. There is also no way that you can force them to help pay the property and neither should you, because then it would mean they would have a claim against you which could result in them being able to sell the house to pay their claims.
Point is, they have nothing to do with the property at this stage. They only get involved if you stop paying, so, if you are in a position to pay off the mortgage and it is to your benefit, do it and the house would be yours unencumbered.
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