How old is your mum, and what do you think is her expectation of your marriage? Don't forget that we are in Africa, where grand children is their inalienable right. If relationship with an old woman is your desire, I can rightly guess that romance is not up in your list. In this case, permit me to suggest, that your mum is your best pick, having courted each other for as old as you are now. 

Why is it called WILL, if your wife tags by, to make contribution. A WILL, is a personal Testament of how your personal Estate, is to be distributed behind you. However, if it is a family Estate, I.e things acquired by two of you, then your spouse must be present as the WILL is drafted. In a nutshell, a WILL, is a personal thing.