Is a contact to Sell , legally binding ?? Or do you need to register it on titled.

First thank you for your time and effort. Very appreciated and needed.
My wife (Philippina)and I have found a house and lot in the San Fernando area that we would like to buy.
And have agreed to terms and conditions with the seller.
The seller is Financing the sale. We will put 600k down, and pay 600k/year until paid in full for a total of 3.5 m.
The seller has offered to let us hold the titled of the property in a safety deposit box with a notarized Contact of sale stating all the condition. Until all monies are paid in full then will transfer the property title to us.
Is this all that needs to be done to be protected ??
Should the Contact to sell be registered on the deed in land titles or something more ??
What is stopped them from saying they loosed the title , getting a new one and re selling the place. Or not honoring the contract?

Yes. The Contract to Sell is considered legally bind once it is signed (by the parties involved in the sale) and notarized. After full payment of the sale, you need to execute a DEED OF ABSOLUTE SALE in order for you to transfer the title under your name before the office of the Registry of Deeds.

Make sure that seller is a legit and real owner of the property. I advise you to conduct thorough verification and due diligence to make sure that the property you are preferred to buy is not a bogus.

Thank you for your time, in Canada, we would register the contract to sell on the deed to stop a second one to someone else from being registered ?? I might be being over protective, but I have been ripped off for 2 m by another loan to someone and no one seems to help us. all they do is give us 10k here and there. It makes me so mad.
I want to try and help make the Philippines a better place, maybe I am just a dreamer, but I will try. I believe she has such great possibilities.

You can also do that here in the Phillippines. It is your discretion if you will register the contract to sell or annotate it in the transfer certificate of title.