advice for legality of property ownership

Good evening po ulit, may issangguni po ako regarding sa problema ng sister ko, naisanla po nya s financing corporation ang bahay nya at natubos na po nya sa lending corporation kya lang po hindi po ibinigay s kanya ang titulo ng kanyang bahay at lupa dhil ang nagbayad po sa pagkakasanla nya ay iyong duktor na interesado pong bumili ng knyang bahay at lupa. Tanong ko po, pwede po ba syang mag back-out sa kasundun nila ng duktor dahil ibenebenta lang nya ang kanyang bahay at lup sa halagang 2M naibigay na po ng duktor ang 500T bilang pantubo sa kanyang naisanlang bahay sa lending corporation, gusto po sana nya na ma areglo na lang na byran nya sa duktor ang kanyang pagkakautang na halagang 500T paunti unti dahil ayaw na po nyang ibenta ang kanyang property. Salamat po sana po ay may laban pa po sya dahil ayaw na po nya ibenta ang bahay at lupa.

OBLIGATION AND CONTRACT-

Obligation derived from CONTRACT is enforceable and it is possible that the contract exist between the owner/mortgagor/vendor and the alleged Doctor who redeemed the mortgaged property from the Lending Institution, and the proposed withdrawal of said owner/vendor/mortgagor for the completion of sales transaction (house & lot) shall constitute a BREACH. However, if the price of house and lot is too low compared to the current selling price, and the doctor offered to buy merely with the intention of taking advantage of the price, the owner/vendor may demand a novation of contract to acquire a right price, and in case of disagreement, the court may choose the price therefor. No person shall be benefited at the expense of the other.