Property distribution in a family

I am explaining my family situation below, and using code names for simplicity. Please advise. SITUATION: Mr. X has two wives. Lets call them W1 and W2. Mr. X stays in a building which is constructed on two plots of land i.e. P1 and P2, which are adjacent to each other. Plot P1 is registered in the name of first wife of Mr. X i.e. W1. While plot P2 is registered in the name of Mr. X himself. From each of the two wives, Mr. X has two sons, thus Mr.X has 4 sons. From W1, two sons named S1 and S2. From W2, two sons named S3 and S4. Now Mr.X wants to prepare a will so that his property can be fairly distributed to his legal heirs. In the will, Mr.X wants to mention that wife W1, who is already the legal owner of plot P1 will continue to own P1, and any building constructed on P1 along with all the movable assets on P1. While P2 (the plot which is currently registered in the name of Mr.X himself) should be given to his second wife W2, along with any construction on P2 and any movable items on P2. In the case of demise of W1, the two sons of W1 i.e. S1 and S2 will be the legal heir of W1 And in the case of demise of W2, the two sons of W2 i.e. S3 and S4 will be the legal heir of W2. QUESTIONS: 1. Legally speaking, are there any things which Mr.X need to take care of before creating above will? 2. Does the two wives (W1 & W2) or fours sons need to take care of anything? 3. Does W1, W2, S1, S2, S3 & S4 need to sign the will? If not, will it be beneficial for them to sign, so that clarity is ensured later on.