Who Pays for????

The only things that I know are understood when you are an attendant is that you will pay for your dress or tux and help plan the shower/bachelor party. I could not imagine asking anyone the pay for my church or cake topper! I don't think there are any 'suppose to' situations (at least not for me)

The invite is issued by the 'hosts' of the wedding, in this case your parents, so it's improper for Fi's parents to be included at the top - Your parents are inviting everyone to their party celebrating your marraige - his parents are not co-hosting.