Does it matter if the sister in law to be, goes to the brides bacholerette party

This decision is a personal one that should be made by the sister in law, based on her relationship with the bride to be.

It is a nice gesture to attend events such as this in order to get to know one another and feel a sense of connection. However, it is not a required thing to do unless the future sister in law is in the bridal party.

No, it doesn't matter, but it might matter to her.

Hopefully, it's not too late...This is very tricky. You did not say if you didn't want to invite her or if she doesn't want to attend. Although this is kind of your day, if you do not get along with her, and you do not invite her, this is going to put a strain on not only your relationship with her and your future husband, but it could strain your relationship with him. Although it's hard, if you are the better person and continue to reach out to her and try to include her in things, you may see a change in her attitude toward you. You will be a hero in your husbands eyes if you always show compassion to his family, no matter what they do or say to you. That does not mean let them walk all over you, but let your husband do the defending. The old adage is true, "You can catch more flies with honey than with vinegar"
If however, she is stating that she doesn't want to go, ask her if you have offended her in some way. It may be a simple understanding that you were totally unaware of. Apologize and ask her to please come, telling her how much it means to you.
If the time has passed and she didn't go or wasn't invited then go to her immediately and tell her how sorry you are for what has happened. Try to do things with her to let her know that you want to be more like sisters than in laws.
I can tell you from experience that this works like a charm, and people whom I didn't get along with are now close to me. Some of them didn't like me for some reason, some of them I didn't really like. This works well not only in family dynamics, but work situations. Soemtimes you find out you were wrong in your assumptions of someone, and sometimes they actually change. Some will even pick up on this and apply it to their lives. You must remain genuine though. This is where it gets hard.

I wish you the best of luck and pray you will have a long and happy life with your new husband and his family. Susu

It would be a good idea to attend. You would not want her to feel slighted . It isn't some kind of tradition not to go.

No let her come she is your "sister" gawd!