Future sister in law as bridesmaid
So me and H2b got engaged last weekend, yay!
Now to the problem. I am unsure of who to have as my bridesmaids. As a couple we decided we would like 4 in each party as H2b thought two would be too few and I want the parties to be symmetrical. He doesn't know who he wants any of his party to be. I accept that, men just work on a different time scale and we have plenty of time. I have decided on my matron of honour and one of my bridesmaids they were easy. The other two are going to take thought.
I am an only child and my H2b is one of three, 1 brother and 1 sister. He has suggested he would like his sister to be a briidesmaid. However as an only child I do not think I should be told who should be my bridesmaid. If I had siblings maybe this would be different.
Also for her age nearly 21, I find the way she behaves and acts as very immature. When we are visiting his family we often find we are treating her like a 10-12 year old. She is also very selfish and I just think she would cause me a great deal of stress on my big day. His mother is very disengaged with life anyway. She didn't even ask how he proposed. Can I get some advice on what to do?
I haven't formally mentioned about her being a bridesmaid but we are going home in a month to show off the engagement ring. I would like to have formulated some form of answer before then as I know this issue will come up.
Thanks in advance for any advice and comments! :-)