There is no etiquette which determines that you should invite your sister-in-laws just because your fiance will be having their husbands as groomsmen. It is your perogative to decide who you would like to be your attendants and you should choose who you want the most. Often there is an 'expectation' from families that certain members will be involved automatically just because they are family. I think you're entitled to have whatever you've always dreamed of and if this involves your close friends then go ahead and invite them. Your sister-in-laws may not have even considered the thought that you might ask them to be bridesmaids or even want to be so you might be worrying about nothing! You could always offer your sister-in-laws some other role in the wedding, maybe get them involved with planning or give them an alternative responsibility on the day (like reading a poem at the service) which will show them that they are still important to you. I'm sure everything will work out fine. Good luck

It is not usual to have a sister in law as a bridesmaid, unless of course you happen to be close friends! Your fiancé gets to choose his groomsmen and you choose your bridesmaids (not him!) I am quite sure that your sister in laws do not expect to be asked and are quite happy to attend the wedding as guests. It is certainly not rude to not invite them to be bridesmaids and you should ask the friends you want. Hope this helps!

It is normal to have 1 or 2 of the grooms sisters as bridesmaids but not sister-in-laws, this is something I have never heard of before! So, to answer your question I would sit him down and explain you have 5 friends very dear to you that you would like as bridesmaids and it would be incredibly hard to choose between them. Do the sister-in-laws have children? If so, you can remind your fiancee that the children would need their Mums to look after them. Are all your friends unmarried? If yes then great, traditionally Bridesmaids should be unmarried which means your sister-in-laws are not suitable. Do your sister-in-laws have small children i.e flowergirl ages? This could be a great way to involve them. I hope this helps and best of luck with your wedding planning.