Mortgage of parents property with an existing will

Dear Sir/Madam, I would like to know if there is a registered will exist for a property (house) owned by my parents can be mortgaged for taking an educational loan (abroad studies) for my brother? We are three siblings, elder two daughters and youngest one son. We daughters are married but we did not get any financial assistances for our marriages (another story of financial problems) and the only thing now left in our parents name is a house. We want the property to be divided into three of us in future and I proposed my siblings to ask my parents to make a registered will about the same (to avoid future disputes). However, my brother says if there is a will exists for that property, then he cannot use that property to take an educational loan? Is this true? Thank you in advance,