Good Evening, Tutors! This is an example case from the book Managing The Law. Can you help me point out the important parts and also the type of law implied here? Thank you!

Ten years ago, Edgar's daughter, Tina, married Hussein. Because the young couple could not afford to buy a house by themselves, Edgar placed a down payment of $90 000 on a home and told his daughter and son-in-law that they could live in the house and that if they paid monthly mortgage instalments of $1000 until the mortgage was satisfied, he would transfer the clear title into their name. Unfortunately, Tina and her parents recently had a falling out. Although Tina and Hussein have regularly paid the monthly mortgage instalments and wish to continue doing so until the mortgage is paid off (which they predict will occur in about seven years), Edgar has purportedly revoked his offer and stated that he intends to pay the remaining mortgage instalments and permanently live in the house himself. Did the parties act with an intention to create legal relations? Was the contract proposed by Edgar's initial offer a bilateral contract or a unilateral contract? Have Tina and Hussein fully accepted Edgar's offer? If not, can Edgar revoke his offer? If it was a unilateral contract, were Tina and Hussein obligated to pay the full mortgage once they began to make instalment payments?